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C I N C P A C - C I N C P O A BULLETIN NO. 3 4 6 15 MARCH 1946

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FLEET MARINE FORCE, PACIFIC C/O FLEET POST OFFICE, SAN FRANCISCO.

Confidential 1 March, 1946

From : Officer in Charge, Japanese Defense Study Group. To : The Commander in Chief, Pacific Fleet and Pacific Ocean Areas, Via : The Commanding General, Fleet Marine Force, Pacific,

Subject: TRUK, transmittal of Japanese defense study of.

References: (a) CinCPOA dispatch 162329 of November, 1945. CinCPOA dispatch 220315 of November, 1945. (b) - - ­

(c) CinCPOA dispatch 270316 of November, 1945,

1* Upon completing its survey of CHICHI JIMA the Japanese DefenseStudy Group proceeded to TRUK on board the USS Castle Rock (AVP 35) in accordancewith references (a), (b), and (c). The Group was organized as set forth belowto carry out its mission of reporting on the Japanese defenses on TRUK, Avail­able intelligence material was studied enroute.

2. The Study Group was organized as follows:

(a) Supervisory group.

NAME RANK ORGANIZATION REPRESENTING

DAVIS, Leonard L. Brig. Gen.,USA 2273d AAC (Hawaii) AFMIDPAC MARSHALL, St.Julien R. Colonel, USMC Hdqts, FMF,PAC FMF,PAC REEVE, Parker M. Colonel, USA Oahu Engr. Ser. AFMIDPAC WEINTRAUB, Daniel J. Captain, USN PHIBSPAC PHIBSPAC PETERS, James M. Commander, USN COMAIRPAC COMAIRPAC •RIDGE, Thomas L. Lt.Col., USMC 3rd MarDiv FMF,PAC MEDINNIS, Charles L. P. Lt.Col., USA Oahu Ord. Ser. AFMIDPAC POPE, Albert L. Captain, USMC Hdqts, FMF,PAC FMF,PAC PORTH, Alfred M. 1st Lt., USMCR Hdqts, FMF,PAC FMF,PAC •Assembly and Publication of Report.

(b) For the purpose of collecting information and preparation ofthe final report the Study Group was divided into sections with the senior officerin charge of each section,

(l) Engineer. (Fortifications, Installations, Roads, Rail­roads, Bridges, Explosives, Demolitions)

NAME RANK ORGANIZATION REPRESENTING

REEVE, Parker M, Colonel, USA Oahu Engr, Ser. AFMIDPAC JAMES, David E. Captain, USA 2805th Engr.Gen.Sr.Bn. AFMIDPAC JAEDTKE, Gilbert H, Lt (jg), USNR 5th Naval Cons. Brig. COMMARIANAS HIROKI, Howard K. 2nd Lt., USA Hdqts, MIDPAC AFMIDPAC NAHLIK, Sylvester R. Carpenter, USNR 5th Naval Cons. Brig. COMMARIANAS

(2) Artillery and Ordnance. (CD,AA, and DP Guns: Tanks, and Vehicles)

NAME RANK ORGANIZATION REPRESENTING

MEDINNIS, Charles L. P. Lt.Col. USA Oahu Ord. S e r . AFMIDPAC DORR, William R. Lt.Col. USMC H d q t e , FMF,PAC FMF,PAC HARRISON, Edward P. Lt.Col. USA Oahu Ord. S e r . AFMIDPAC MENDENHALL, George E. Lt (Jg) USNR JICPOA JICPOA WYCOFF, DeWltt D. 2nd Lt. USMCR 3 r d MarDiv FMF,PAC

(3) Beaches and Hydrography; Naval Vessels and Installations.

NAME RANK ORGANIZATION REPRESENTINq

WEINTRAUB, Daniel J. Captain, USN PHIBSPAC PHIBSPAC GUTHRIE, James T. Lt.. USC & GS PHIBSPAC PHIBSPAC HELANDER, Melvin Lt (jg), USNR INTERPRON 2 COMMARIANAS ZIRKELBACH, Harry W. Ensign, USNR MEIU 4 MEIU 4

(4) Signal Communications. NAME RANK ORGANIZATION REPRESENTING

POPE, Albert L. Captain, USMC Hdqts, FMF PAC FMF,PAC CLARK, John A. Lt (Jg), USNR JICPOA JICPOA HURLBUT, Franklin C. Ensign, USNR COMMARIANAS COMMARIANAS EVANS, William A. Rad. Elec. NOB, GUAM COMMARIANAS

(5) Strategic and Tactical Subjects;(History; Order of Battle; Panoramic-Photographic Terrain Study; Tactical Dispositions;Infantry Weapons Dispositions; Medical and Sanitary Condi­tions).

NAME RANK ORGANIZATION REPRESENTING

GOWER, Elmer B. Major, USA Hdqts, AFMIDPAC AFMIDPAC MALLON, James R. Captain, USMCR 3rd MarDiv FMF,PAC SHEEHAN, Richard G. Ensign, USNR JICPOA JICPOA

(6) Aviation,

NAME RANK ORGANIZATION REPRESENTING

PETERS, James M. Commander, USN COMAIRPAC COMAIRPAC

3. The Study Group arrived at TRUK on 13 December, 1945 and commenceda study of the Japanese defenses Immediately. The desired data was collected by 23 December, 1945 and the Study Group departed.

ST. JUKEEN R. MARE Cblonel, USMC

HEADQUARTERS FLEET MARINE FORCE, PACIFIC

C/O FLEET POST OFFICE, SAN FRANCISCO.

Confidential 2 March, 1946.

1st Endorsement on ltr fr OinC, JapaneseDefense Study Group to CINCPAC-CINCPOA,dtd 1 March, 1946.

From : The Commanding General, To :

The Commander in Chief, Pacific Fleet and Pacific Ocean Areas. Subject:

TRUK, transmittal of Japanese defense study of. 1.

Forwarded,

ROY S. GEIGER

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CINCPAC-CINCPOA Bulletin No. 3-46, JAPANESE DEFENSES ON TRUK ATOLL, CAROLINE ISLANDS.

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TABLE OF CONTENTS

TITLE PAGE NO TITLE PAGE NO.

GEOGRAPHY 1

SUMMARY 6

A SHORT HISTORY OF THE MILITARY DEVELOPMENT OF TRUK 8

JAPANESE ORDER OF BATTLE, TRUK ISLANDS 9

PANORAMIC PHOTOGRAPHIC TERRAIN STUDY 12

ARTILLERY AND "ORDNANCE 22

Sources of Information 22 Development of the Defenses 22 Equipment Available 22 Artillery Tactical Control 22 Artillery Fire Control 22

Artillery Positions On Barrier Reef Islands 23 Description of Individual Batteries 23

Artillery - General Remarks 23

Maintenance and Repair Facilities 34 Total Quantities of Fire Control Items 36 Total Quantities of Vehicles 38 Total Quantities of Weapons and Ammunition 38

ENGINEERING 46

Military Engineering 46

Army Communications

Radio Radio Countermeasures Radio Intelligence Radio Direction Finders Wire; Telephone Radar Power Equipment Visual Pigeons Codes and Ciphers Air-Ground Communications Meteorlogical Stations Supply and Repair

NAVAL ACTIVITIES

General Mine Warfare Defense of the North and South Passes Details on Minefields in TRUK Atoll Obstacles Vessels Navy Ships and Boats Naval Communications Hydrographic Information Conditions of the Sinking of Submarine 1-169 The Attack on TRUK by the British Task Force

101

101 103 103 103 103 103 103 103 103 103 103 103 103

107

107 116 118 123 124 125 125 126 126 127 127

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Engineer and Construction Troops 46 > Organization of the Ground 46 BEACHES 128 Q Fortifications 48 Z Obstacle Construction Types 52 General 129 Searchlights 58 Beach No. 1 129 Mines, Mine Warfare, Booby Traps, Explosives and Demolitions 58 Beach No. 2 129 Camouflage 58 Beach No. 3 130 Chemical Warfare 58 Beach No. 4 131 Field Utilities 62 Beach No. 5 131

Beach No. 6 132 General Construction 63 Beach No. 7 133

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Roads, Trails, and Railroads 67 Wharves and Docks 67 Bridges and Causeways 67 Installations 70 Underground Installations in General 82 Fixed or Permanent Utilities 82

SIGNAL COMMUNICATIONS 86

General 86 Navy Communications 86

Radio 86

Beach No. 8 Beach No. 9 Beach No. 3.0 Beach No. 11 Beach No. 12 Beach No. 13 Beach No. 14

AVIATION

General Construction of Air Facilities Disposition of Aircraft

133 134 134 136 136 137 137

138

138 138 138

Radio Countermeasures 92 Radio Intelligence 92

UJ Destruction of Japanese Air Power at TRUK 139 CO Z mMEDICAL & SANITARY CONDITIONS 143

Radio Direction Finding 92 u. UJ Wire 92 Introduction 143 Radar 94 aGeneral 143

Summary 98 Ul Medical 143 CO Power Equipment 100 144 Ul VIsual 100 Sanitary Conditions ZPigeons 100 145 Codes and Ciphers 100 APPENDIX I Air-Ground Communications 100 Meteorlogical Stations 100 APPENDIX II Supply and Repair 100 150

APPENDIX III

HI

TABLE OF CONTENTS

o PART TWO o

I

.LIST OF ENCLOSURES

2 m (A) ENEMY DEFENSIVE INSTALLATIONS, TROOF DISPOSITIONS, AND FACILITIES, DUBLON

ISLAND, SCALE 1:12,500, CONFIDENTIAL.

z (B) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, MOEN I— ISLAND, SCALE 1:25,000, CONFIDENTIAL. UI

(C) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, FEFAN ISLAND, SCALE 1:25,000, CONFIDENTIAL.

(D) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, PARAM, o UDOT AND EOT ISLANDS, SCALES 1:12,500 AND 1:25,000, CONFIDENTIAL.

Z (E) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, ETEN AND UMAN ISLANDS, SCALE 1:12,500, CONFIDENTIAL.

(F) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, NORTH

V TOL ISLAND, SCALE 1:25,000, CONFIDENTIAL.

z (G) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, WEST TOL AND SOUTH TOL, SCALE 1:25,000, CONFIDENTIAL.

CO (H) ENEMY DEFENSIVE INSTALLATIONS, TROOP DISPOSITIONS, AND FACILITIES, TRUK BARRIER REEF, SCALE 1:250,000 CONFIDENTIAL. Z

(I) LOCATION OF GROUND PHOTOGRAPHS, TRUK ATOLL, SCALE 1:96,585, CONFIDENTIAL. _J CO

(J) H. 0. CHART 6046, REPRINTED. UI

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COMMENT ON T.HE NUMBERING OF PHOTOGRAPHS

Individual photographs, the first of which appears on page 20, are sequentially numbered to facilitate reference thereto in the written body of the report. Immediately f 01 lowing th'e sequential number is the "PM" number in par.ent he s is , z i.e., Picture No. 1 (PM 572), which indicates the basic number of a picture in o APPENDIX III /Ground Photographic Reference Data) and on the map ent it led

CO "LOCATION OF GROUND PHOTOGRAPHS" in PART TWO. This procedure was adopted in UI CO order to maintain a cross-reference between the 451 photographs appear ing in

this publicat i on and the total of 575 photographs that were taken and are listedZ UI in APPENDIX III and on the map entitled "LOCATION OF GROUND PHOTOGRAPHS" in

PART TWO. It should be noted that the photographs contained in the panoramic strips have no sequential numbers since the individual photographs contained-therein are" not referred to in the written body of the raPort. Aerial Photo-UI

CO graphs are given separate numbers, i.e.. Air. Photo No. 1, and appear only in UI the sections entitled "BEACHES" and "AVIATION"- See APPENDIX III for the lo-Z cation of all photographic negat ives in the event copies of phot ographs are

desired.

FIGURE NO.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26A 26B 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

LIST OF FIGURES IN PART ONE

TITLE

TRUK ATOLL CAROLINE - MARIANAS AREA PANORAMIC PHOTOGRAPHIC STATIONS ARTILLERY & SEARCHLIGHT POSITIONS (TOL) ARTILLERY & SEARCHLIGHT POSITIONS (FEFAN) ARTILLERY & SEARCHLIGHT POSITIONS (UDOT & EOT) ARTILLERY & SEARCHLIGHT POSITIONS (UMAN) ARTILLERY & SEARCHLIGHT POSITIONS (DUBLON & ETEN) ARTILLERY & SEARCHLIGHT POSITIONS (PARAM) ARTILLERY & SEARCHLIGHT POSITIONS (MOEN) 15 CM GUN POSITION (N. TOL) 155 MM COAST DEFENSE BATTERY (UMAN) 14 CM GUN BATTERY (S. UMAN)ANTI-AIRCRAFT BATTERY EMPLACEMENT (FEFAN)ARMY DIVISIONAL COMMAND POST (DUBLON)3D INFANTRY BATTALION COMMAND POST, 69TH REGT.,(DUBLON)MT. UBAN, 341ST BATTALION COMMAND POST (FEFAN)NAVAL BATTLE COMMAND POST CAVES (DUBLON)ANTI-TANK OBSTACLE GAS PROOF SHELTER (DUBLON)LOCATION OF PIERS (TRUK ATOLL)DUBLON ISLAND SUBMARINE BASE 4TH ShIP REPAIR DEPT. (DUBLON)4TH COMMUNICATION UNIT TRANSMITTING STATION NANKO DOCK OR CHARE AREA FUEL OIL TANK FARM & OIL SUPPLY PIERS DUBLON ISLAND SEAPLANE BASE SUPPLY WAREHOUSE AREA COMMUNICATION UNIT RECEIVING STATION 4TH NAVAL HOSPITAL (DUBLON)104TH AIR FORCE ARSENAL AIRFIELD NO. 1 (MOEN) AIRFIELD NO. 2 4 SEAPLANE BASE ETEN ISLAND AIRFIELD AND FACILITIES PARAM AIRFIELD UMAN ISLAND RADIO STATION DUBLON ISLAND WATER DISTRIBUTION SYSTEM MOEN ISLAND WATER DISTRIBUTION SYSTEM POWER DISTRIBUTION SYSTEM (DUBLON)POWER DISTRIBUTION SYSTEM (MOEN)PACIFIC AREA RADIO SYSTEM (NAVY)COMMUNICATIONS: SUBMARINE CABLE, BURIED CABLE,

AND AERIAL CABLE NAVY TELEPHONE SYSTEM (DUBLON)RADAR COVERAGE DIAGRAM PACIFIC AREA RADIO SYSTEM (ARMY)ARMY TELEPHONE SYSTEM (DUBLON)DEFENSIVE COMMUNICATIONS SYSTEM (DUBLON)MATSUSHIMA BRANCH (4TH REPAIR DEPT.)IMPROVISED TORPEDO BOAT ANTI-TORPEDO NET FOR BATTLESHIPS 1 MAN TORPEDO ATTACK BASE 1 MAN TORPEDO (SIDE VIEW)MINEFIELDS, SUNKEN SHIPS AND BUOY OBSTACLES (TRUK)TYPICAL SMALL MINE LOCATIONS TYPE 2 - UNDERWATER MAGNETIC DETECTOR DIAGRAM OF INTERIOR OF GUARD STATION (UMAN) SUSPENDED TYPE MODEL 1 HYDROPHONE (UMAN) DIAGRAM OF CONTROLLED TYPE 92 MINES IN NORTH PASS BUOYS USED TO OBSTRUCT SMALL CRAFT (DUBLON) STEEL RAIL UNDERWATER OBSTACLES AND COCONUT LOG OBSTACLES LOCATION, OF LANDING BEACHES (TRUK ATOLL) PROFILE OF BEACH NO. 1 (DUBLON) PROFILE OF BEACH NO. 2 (DUBLON) PROFILE OF BEACH NO. 3 (DUBLON) PROFILE OF BEACH NO. 4 (DUBLON) PROFILE OF BEACH NO. 5 4 6 (ETEN) PROFILE OF BEACH NO. 7 (MOEN) PROFILE OF BEACH NO. 8 (MOEN) PROFILE OF BEACH NO, 9 (MOEN) PROFILE OF BEACH NO. 10 MOEN)PROFILE OF BEACH NO. 12 ;FALA-BEGUETS)PROFILE OF BEACH NO. 13 ,ULALU)

PAGE NO,

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I GEOGRAPHY

i i r 1 1 r J 1135* 140*^ 150* 'ASUNCION 0 AGRIHAN ' PAGAN eALAMAGAM 'GUGUAN

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FIGURE N0.2-CAR0LINE-MARIANAS AREA 135? , 1 • |l40? 1 1 1 Il45t . < . ll50? 1 1 1 1 1 1

GEOGRAPHY.

TRUK Atoll consists of a group of about 84 coral and basaltic islands, A bar­rier reef, roughly circular in shape encloses the larger islands in a lagoon about 30 miles in diameter. Six major islands lie within the lagoon. They are DUBLON, TOL, MOEN, FEFAN, UDOT and UMAN.

The greatest elevation is MT. TUMUITAL, 1,422' high, on the southeast corner of TOL, Other conspicuous mountains are MT. TOLOMAN on the southwest of DUBLON, MT. TEROKEN, in the west central area of MOEN and the four summits that extend down the center of FEFAN. Sand beaches are rare on the large islands, but a few small beaches are found.

Altogether within the lagoon there are 14 volcanic, basaltic islands and 25 small coral islands. The small islands are surrounded by fringing reefs, and oc­casional mangrove growth, but in general have sandy beaches and a low sandy in­terior covered with palm trees.

The large islands are fringed by wide reef and mangrove swamps with steeply rising hills and mountains Just beyond the mangroves. The result is that the amount of useful land area at TRUK is far less than appears at first glance. Jap­anese development fringes the shorelines, considerable areas of the mangroves on DUBLON and MOEN having been filled for construction purposes. The fill is taken from the sides of the hills resulting in still steeper hills and cliffs. This is especially noticeable along the south side of DUBLON, where a cliff rises Just be­yond the road.

On the great atoll reef there are almost 50 islets, small and widely separat­ed. In the southeast section, there is a group of sand islands which roughly com­pare in size and characteristics with islands of the MARSHALL and GILBERT area.

1 1 1 1 1 1155* I606

TRUK ATOLL, E q u i v a l e n t E n g l i s h - J a p a n e s e p l a c e names .

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Name on Char t

TRUK ATOLL ( I s l a n d s ) MOEN DUBLON FEFAN UMAN ETEN UDOT EOT FALA-BEGUETS TOL PATA (NW p a r t TOL) POLLE (SW p a r t TOL) ONAMUE ULALU KUOP ATOLL . . . . TARIK TSIS PARAM OTTA I . MESAGON I . . . . . UIJEC I* FANAN I . SALAT I . MOR I . P I S I . FALEU I . TONELIK I . OLLAN I . NORTHEAST I , NORTH P a s s • - • • NORTHEAST P a s s SALAT P a s s ULIGAR P a s s OTTA P a s s SOUTH P a s s . . . . PIAANU P a s s

J a p a n e s e Name

TORAKKU SHOTO HARU SHIMA NATSU SHIMA AKI SHIMA FUYU JIMA TAKE JIMA GETSUYO TO MAE SHIMA KAYO TO SUIYO TO MOKUYO TO KINYO TO KOYO TO NICHIYO TO KUNTO SHOTO HOSHI SHIMA USU SHIMA KAEIDE SHIMA OTA SHIMA MASU SHIMA U J I SHIMA HANA SHIMA SARA SHIMA UMA SHIMA KITA SHIMA MINAMI SHIMA NE SHIMA A I O I JIMA U JIMA KITA SUIDO NOKUTO SUIDO SARSHIMA SUIDO HANASHIMA SUIDO OTASHIMA SUIDO MINAMI SUIDO NISHI SUIDO

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Approximate distances (nautical miles) from TRUK Atoll (ETEN Ancnorage) to:

NOMOI 165 NAURU 1005 PORT MORESBY 1050 PONAPE 370 MARCUS 1020 MAJURO 1160 WOLEAI 480 PALAU (KOROR) 1035 TARAWA (BETIO) 1305 GUAM 565 WAKE 1095 ESPIRITU SANTO 1650 SAIPAN 590 TOKYO 1842 FUNAFUTI 1875 ZKAVIENG 800 MOMOTE Airfield 635 MIDWAY 2170 RABAUL 695 ENIWETOK 660 SUVA (VITI LEVU) 2220 o WEWAK 820 KWAJALEIN 955 PEARL HARBOR 3075 CO LORENGAU 640 HENDERSON Field 1120 1 LU

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WEATHER. z LU

TRUK lies in the hot, rainy belt of the equatorial Pacific. Temperature aver- aages 80° with little deviation during the year. Rainfall averages nearly 130" a LU year. TRUK has a fairly well defined seasonal change from 7" in the driest month CO (January) to 13" in the rainy summer months. The dry season lasts from January to LU

March and although this period has less precipitation than the summer, rainfall is zstill considerable with average amounts of 7H or 8" and with squalls and overcast skies not infrequent. The rainy season lasts from June to October.

From December to May the northeast trade blows almost constantly with an aver­age velocity of 15 knots, occasionally exceeding 30 knots. During May and June the northeast trades decrease in frequency and intensity with Increasing winds from east-southeast. From July to November winds are light and variable with frequent calms and blowing mostly from directions between east and south. The winds usually fall off at night and increase again during the morning.

SUMMARY

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HISTORY.

On 2 September, 1945, the surrender of all Japanese controlled islands under the TRUK headquarters was accepted. Prior to November, 1940, TRUK was used chiefly as an anchorage for the 4th Fleet (organized November, 1939)• Little effort was made to garrison the establishment before January, 1944. At TRUK in June, 1945, there were 24,061 Navy personnel and 14,299 Army personnel.

The Japanese were engaged in continuous offensive accion from December, 1941, t'o February, 1944. After the American task force raid at the latter date, the main force of the Japanese fleet left TRUK and the naval base was, thereafter, to stand alone. After the loss of the MARIANAS in June-July, 1944, reinforcement of TRUK became impossible.

"** The almost complete isolation of TRUK necessitated the adoption of a defensive organization to repel any invasion by American forces. The Japanese Army and Navy exercised a joint command and TRUK was divided into five defense districts. Where possible, installations were concentrated on the main Islands and in most cases lo­cated in caves or bomb-proof structures. In June, 1945, the Japanese reached the height of their defensive power.

The TRUK garrison lacked adequate quantities of planes, artillery, ammunition and construction materials, but in spit of this they stated that they were satis­fied with their overall situation. They apparently felt their lack of equipment could be countered by the "Bushldo" spirit.

DEFENSE PLAN,

The Japanese defense plan of TRUK called for a strong defense of MOEN, DUBLON, FEFAN and UMAN, with units for observation and delaying actions stationed on the other islands within the lagoon and on the barrier reef. Observations revealed .that the distribution of men and materiel was carried out in accordance with this plan. However, the skill with which the organization of the ground and construction work

CO was carried out depended solely on the ability of individual commanding officers; Q apparently the high command allowed considerable latitude for the initiative of

CO UJ CO

Z

CO UJ

Z

Modern fire control devices were almost non-existent. There were only four AAA directors, few range or height finders and no fire control radar. AAA not equipped otherwise used an improvised forward area sight. Seacoast artillery re­lied on registration markers and buoys at known ranges. There were 20 search­lights controlled by various gun battery commanders with little central supervision from the Navy CP on DUBLON.

Ammunition storage was in the battery position cave or in a nearby revetment, and ready boxes were generally Installed at gun positions.

Intrabattery tactical communication was primarily by telephone supplemented by buzzer and speaking tube systems. Interbattery communication was principally by telephone and radio supplemented by runners and carrier pigeons.

Maintenance and repair facilities, until the bombing of 30 April, 1944, were capable of making very extensive repairs including 5th echelon at the Naval Air­force Construction Department and Garrison shops. The bombing reduced these fac­ilities to roughly 10 to 20 percent of their former effectiveness.

ENGINEERING.

oZu

The Japanese on TRUK, as elsewhere, were trying to conduct a major war with inadequate military materiel. To this fundamental error they added an unbalanced sense of proportion which gave all-out backing to naval projects regardless of their, strategical or tactical value. For example, age old necessities such as roads were neglected, while heavy weapons were moved over seemingly impassable terrain into caves.

Organization of the ground, fortifications, and workmanship were generally excellent, though often lack of attention to routine details such as ventilation, drainage and personnel safety was apparent. The over-all accomplishment of the Japanese was but fair in all sorts of fortifications including obstacles, mine warfare, explosives and demolitions. Camouflage in the tropical terrain was ex-

Z all subordinate echelons. cellent to superior, though it would be interesting to time the gun crew going into action against a land target where there were a dozen sturdy banana stalks in

CO The guiding principle in defense was to annihilate assaulting forces at the the field of fire of th*ir piece less than 61 from the muzzle. beach. This was virtually dictated by the relatively small land masses involved.

LU Plans were drawn up to provide for mutual support among the islands by means of In offensive chemical warfare the Japanese could do nothing but lay down a Z amphibious reserves, and it was highly probable that unless all defending forces few small smoke screens. Defensively they were only fairly well prepared with had been pinned down by simultaneous assaults at each island, an assault force gas masks, collective protectors and properly designed ventilation. Their last-

ditch Installations were located at elevations where it would be very difficult to o

Z

o

might have found itself under attack on the flank or rear by Japanese troops ar­riving by landing craft from nearby islands. Special emphasis was placed on achieve lethal concentrations of gafe, and to deliver flame.

Roads, trails and bridges were poor to fair in construction. Traffic circu­training in night maneuvers for counter-attack, including the use of landing craft and tanks, in order to eliminate or contain any airborne attackers who might land within the defense lines.

A superficial Inspection of the positions and dispositions throughout TRUK leads to the conclusion that the Japanese had not entirely abandoned the idea of

lation was Inadequate due to poor drainage, narrow widths and ungraded road metal. The roads oarrying the least traffic were the best and appeared to be the oldest, indicating that whatever merit the roads did have was of prewar vintage and not a characteristic of wartime construction.

retaining mobility in order to go underground. It is probable, however, that this was because they had too little equipment, material and supplies, too few people, and too little time to complete their underground installations before the end of hostilities.

ARTILLERY AND ORDNANCE.

Utilities, including water supply, power and light, fire fighting, and preven­tion, sanitation and refuse disposal were inadequate. Engineer supply was very poor both in respect to materials furnished and facilities for their receipt, storage and issue.

TRUK was protected by numerous but relatively light artillery pieces. The inventory lists 101 Army guns (75 to 105mm.) in 86 battery positions; 85 naval wea­pons (75 to 200mm.) in 36 battery positions; and 302 automatic weapons (13 to 25mm.). Ammunition in varying quantities was on hand for each type of weapon.

Following our air raids of February, 1944, the defensive plan was changed. Heavy artillery was withdrawn from reef positions and relocated on the principal inner islands; except for AAA and a few other batteries, most artillery was em-placed in caves or in cut and cover type emplacements. This program had been cur­tailed by lack of time and materials. Only two batteries could fire effectively beyond the reef. Most of the heavy artillery was for minefield and inshore defense.

General tactical control of artillery was exercised at 4th Fleet and 31st Army Command Posts on DUBLON, but in the final defense plan each island commander controlled his own units. Artillery on the various islands was capable of mutual support.

Engineer ana construction troops were inadequate in all three essentials: staff, trained manpower and equipment. The engineers and "pioneers" lacked the tools and equipment that should have differentiated them from other combat troops. The naval construction forces were more numerous and better equipped than the eng­ineers or "pioneers" but were too few for the Navy's needs alone.

NAVAL ACTIVITIES.

When the primary mission of TRUK changed to the defense, naval units impro­vised weapons, such as the one-man controlled torpedo, and the torpedo-carrying landing craft. The mine-fields in the passes and inside the reef, and small model beach mines had previously been the main protection against invasion.

Naval shore establishments were never extensive without drydocking facilities for large ships and with few repair facilities. Larger ships were refueled from tankers in the harbor, or by oil barges from an oil pier on DUBLON.

X

SUMMARY

o o

KJ OC

LU

O a. Z

BEACHES,

Suitable sites for landing ships were rare. All the large islands lay inside the barrier reef and are fringed by wide reefs and mangrove swamps, backed by steep hills and mountains. Sand beaches were rarely found on the larger islands and those existing were usually inaccessible to landing ships due to reefs. Dispersal areas on the whole were restricted by swampy, hilly, or wooded ground, and movement of vehicular traffic was difficult.

Th smaller islands were also surrounded by fringing reefs and occasional man­grove gv- vth, but generally had sandy beaches and a low, sandy, wooded interior.

Attempts were made to approach possible beaches in a Japanese landing craft "DAIHATSU", but normally the craft grounded on passing over the fringing reef. Average depth of water- over the reef was 2.5 feet.

dry batteries, and all of their telephones were local-battery, their most acute shortage was dry batteries. They were also short of spare parts and radio tubes. The Army communication system was not capable of efficient operation at the end of hostilities.

Our bombing and shelling of TRUK had destroyed or damaged most of the instal­lations above ground with the exception of the radars, which were practically un­damaged. Virtually all Important installations had been moved underground prior to our attacks, so little serious damage to the overall efficiency of the system resulted.

AVIATION.

TRUK was originally a major staging base to the SOLOMONS, RABAUL, the MARSH­SIGNAL COMMUNICATIONS. ALLS and GILBERTS and was well defended by air, but in the carrier strikes of Feb­

ruary and April, 1944, such damage was done that the base never recovered. Each z

TRUK was primarily a naval installation and as such the major part of the sig- raid destroyed nearly all aircraft on hand at the time, and all air facilities nal communications was operated and controlled by the Navy. Army communications were severely damaged and much material destroyed. Plans for expanding air facil- CO

ities were given up since they were hard pressed in repairing what was left. After were limited to tactical use in the atoll inner defense. the capture of the MARIANAS, American planes methodically destroyed practically all facilities above ground, and the Japanese found it difficult to keep even runways Long range and internal administrative communications operated efficiently, operational. but control of subordinate units during tactical operations was not evident in the

existing signal plan.

az CO

Finally nothing operated from TRUK but a few planes for reconnaissance of LU

The communication equipment was, in general, of fairly good construction and ULITHI and the MARIANAS, and the base could have been nothing but a staging point reasonably efficient, although the general design was somewhat out of date. No even if aircraft had been available. moisture proofing or fungus-proofing was apparent in any of the equipment, and the MEDICAL. Japanese claimed considerable failures due to moisture.

zo

TRUK had fairly good search radar protection, but the equipment was out of date No fire control or searchlight control radars were installed, and the search radars could give little more than the general direction of targets.

The isolation of TRUK since June-July, 1944, had caused shortages of most com­munication supplies. However, the Navy system could have operated for several months with little loss of efficiency and considerably longer without being ser­iously hampered. Their main shortages were, battery acid, dry batteries and radio spare parts, (especially tubes).

The Army and Navy at TRUK maintained separate medical facilities. Each had a ' OC

base hospital on DUBLON with branch hospitals on the larger islands, and sickbays or dispensaries located near military activities scattered throughout the islands.

Supplies were, in general, adequate; X-ray film and carbasone was available in limited quantities. There were sufficient medical officers and corpsmen, but the hospitals were dirty, crowded and unsanitary by American standards.

Zi OC

The most prevalent diseases were malnutrition, beri-beri, tuberculosis, amoe­bic dysentery, paratyphoid A, ,and WEIL1s disease; dengue was sporadic, occasionally z

oArmy communications were hardest hit by isolation because they depended ex- reaching epidemic heights. No malaria, typhus or cholera were evident. tensively on supplies furnished by the Navy. The Navy1s shortage of materials and CO

Sanitation control was noted by its absence. There was little central super- UJ the lack of close cooperation between the services further aggravated the sit-CO

uation. Since most of the Army radio equipment was small portable sets employing vision of sewage and waste disposal, fly and rat control, individual water supply, Zor prevention of spread of intestinal diseases.

CO Ul

Z

A SHORT HISTORY OF THE MILITARY DEVELOPMENT OF TRUK ATOLL

On 28 August, 1945, a message was dropped by plane on one of the main islands of the TRUK Atoll and was followed at 0700, 30 August, 1945, by the arrival of the USS STACK (DD) and USS OSMUS (DE). The STACK carried Brig. Oen. L. D. HERMLE, USMC, and a party of 12 officers which informed Rear Admiral SUMIKAWA, Chief of Staff of the 4th Fleet, and five other Japanese officers of the requirements preliminary to surrender. This party also handed the Japanese a copy of the Articles of Surrender which were to be signed at a later date.

Aboard the USS PORTLAND on 2 September, 1945, Vice Admiral George D. MURRAY, 2 USN, Commander MARIANAS, accepted the surrender of all Japanese controlled islands under the TRUK Headquarters from Lt. G-en. Shunzaburo MUG-IKURA, Vice Admiral Chuichi HARA, and Mr. AIHIRA, a representative of the South Seas Government sta­tioned at TRUK.

Lt. Gen. MUGIKURA, who had assumed command of the 52nd Division in November, Z 1941, was ranking officer and was appointed commander of the 31st Army on 20 Jan­

uary, 1945, Vice Admiral Chuichi HARA, Commander-in-Chief of the 4th Fleet, came LU to TRUK on 23 February, 1944. The headquarters of the 31st Army and the 4th Fleet were both on DUBLON.

=3

According to Japanese sources little effort was made to garrison TRUK before January, 1944, and at the height of its power in June, 1945, the Japanese Navy had

o 24,061 men and the Army 14,299 men stationed there. The Army and Navy forces were based as follows:

Z PERSONNEL DUBLON ETEN MOEN FEFAN PARAM UMAN UDOT TOL Army 3,242 2,962 2,914 365 873 748 3,150 Navy 4,485 462 578 2,572 827 1,417 1,025 6,220

fiL

2= The remainder was scattered throughout the lesser islands-

The 4th Fleet Headquarters was established at TRUK on 10 November, 1943. The 31st Army Headquarters was organized on 20 January, 1945. The establishment or co arrival of other Naval and Army units was as follows: Q

Z NAVAL UNITS DATE

4th Office of Admin. and Supply. 15Dec40 z 4th Munitions Dept. 15Dec40

4th Construction Dept. Dec40 o 41st Naval Guard Force Nov40 43rd Naval Guard Force Dec44 < 47th Naval Guard Force 48th Naval Guard Force to 49th Naval Guard Force May45 4th Harbor Department 25Aug41 O 104th Naval Air Depot May42 4th Naval Hospital 21Aug42 17th Air Corps Dec41

ARMY UNITS

52nd Dlv. Hq. 69th Inf. Regt. Signal Unit Field Hospital Tank Unit Transportation Unit Ordnance Serv. Unit Intendance Serv. Unit 150th Inf. Regt. 9th Ind. Eng. Regt. 2nd & 8th Det.reorg. as

51st 1MB. 11th Ind. Mixed Regt.

DATE

4Jan44 4Jan44 4Jan44 4Jan44 18Feb44 18Feb44 18Feb44 18Feb44 18Feb44 16Apr44

after 16Apr44 18Sep44

The 17th Naval Air Corps and various other units, which arrived from 1942 to z 1944 when the Japanese air arm was virtually inoperative, were combined to form o the EAST CAROLINE Air Unit. CO LU CO Prior to 15 November, 1940, (the date of the organization of the 4th Defense Z Unit on DUBLON) TRUK was used chiefly as an anchorage for the 4th Fleet which had LU been organized in November, 1939. The 4th Defense Unit was originally a part of LU the 5th Base Unit having headquarters on SAIPAN, and lt had about 850 personnel. LU However, in November, 1942, the Defense Unit became the 41st Naval Guard Force, O and was still in existence at the end of the war. LU CO

After December, 1941, there was a period of continuous offensive action and TRUK was used principally as a fleet base—the fleet being engaged in attacks in the SOLOMONS and MARSHALLS areas. As the advance of the Americans in the SOLO­MONS became more and more successful, TRUK was used as a staging area for airplanes which were to be transshipped into a more active area. After the American task force raid of 17-18 February, 1944, the main force of the Japanese fleet left TRUK. There­after, TRUK was to stand alone.

TRUK was divided into five defense districts—MOEN, DUBLON, FEFAN, UMAN, and the Western defense district with Headquarters on TOL Island. The Japanese placed the stress on the first four of these which were known as the "Season Islands". The Navy was to take charge of surface and air defense, the stress in the case of the former being placed on the area inside the atoll. By agreement between the 31st Army and the 4th Fleet, the senior officer on each island was named as the over-all commander.

DEFENSE DISTRICTS ARMY COMMANDERS

DUBLON (ETEN) Col.Tameichi SHIBANO MOEN (FALO) Col.Keizo HAYASHIDA UMAN Maj.Kyuichi KONDO FEFAN Maj.Hldeakl MORI PARAM MaJ.Eiji SHIBATA Western(Hq.on S.TOL) Maj.Gen.Kanenobu IJUIN

S.TOL Maj.Jisaku YOSHIDA N.TOL Capt.Shigekl MORI W.TOL MaJ.Jofuku SAKAMOTO UDOT Capt.Kaneori FUKUTOME

NAVY COMMANDERS

Rear Admiral Hiroshi KOJIMA Capt. Yoshimitsu IMAZATO Rear Admiral Tomotaro MIURA Capt. Furuya YOSHIRO Capt. Furuya YOSHIRO Rear Admiral Hiroshi KOZIMA

The Army units on TRUK—the 52nd Division, the 9th Independent Engineer Reg­iment and the 51st Independent Mixed Brigade—had the mission of defending TRUK against the Anglo-American forces by joint action with the 4th Fleet and air forces. They emphasized the following: anti-tank warfare, well-mined waters and beach ob­stacles, strong and persistent delaying actions, strong positions among rocky cliffs, and steps to make TRUK self-sufficient in food.

The Japanese did not place great reliance on airplanes because of the great attrition rate and the impossibility of getting more from JAPAN after their com­munication lines were cut off. Their plan was to use those planes which were al­ready on TRUK until such time as enemy attacks should make it more feasible to remove them, in which case they would be based at PONAPE, NAMOI and ENDERBY.

In July, 1944, the mounted guns on some of the small islets of the reefs were removed to the main islands inside the atoll for the following reasons: (1), to place the batteries in caves, rather than in the open so as to gain more protec­tion from bombardment and bomblngj (2), to lay stress on the attack of ships which might manage to get inside the atoll, and to gain mutual support between batteries; (3), to protect the main islands as long as possible.

Wire was strung between buoys on the surface at W.MOEN and N.DUBLON. This was done in front of possible landing points and the aim was to forestall any landing attempt.

The Japanese expected no great help from their anti-aircraft guns as they were all short of ammunition. After the loss of the MARIANAS in June and July, 1944, reinforcement of TRUK became impossible, save by submarine, and the garrison went on short rations.

The Army and Navy exercised a Joint Command—and the Japanese stated that there was no serious difference of opinion between the Army and the Navy or between in­dividuals—but when land action started, the Supreme Commander was to be Lt. Gen. MUGIKURA.

In addition to the 9,895 natives scattered over the larger islands of TRUK, there were 793 natives of NAURU, brought to TRUK by the Japanese; 1,590 Japanese civilians; 6 Germans; 7 Spaniards; and 1 Swede. They were forbidden to approach any defense installation. The natives were impressed into semi-slavery and were used mostly for roadwork.

The following information on the natives and the history of the Japanese military activity on TRUK was gathered from an interview with a priest who came to TRUK in 1927. Some of his statements do not agree with those made by the Japan­ese.

The missionaires came to TRUK in 1911 and were followed by the Spanish mis­sionaries in 1920. During the war there were about a dozen missionaries scattered throughout the TRUK Islands and six sisters lived on FEFAN. These sisters, how­ever, left in September, 1942, and were thought by the priest to have gone to PO­NAPE, followed by two of the brothers.

I

A SHORT HISTORY (CON'T) JAPANESE ORDER OF BATTLE Z UI

The priest stated that when he first came to TRUK the only Japanese present were civilians. The Navy started fortifications in 1931 and 1932 and the Army in the latter part of 1942 and 1943 by which time, the priest estimated about 10,000 had arrived. By 1940, the natives and missionaries were made to stop all com­munication with the outer world.

According to the priest, the first island on which the Japanese concentrated their attention was ETEN. They told the natives that they were merely fixing up the islands for fishing purposes. Then followed in turn, DUBLON, FEFAN, and UMAN. MOEN was one of the last Islands to receive the attention of the.Japanese, but according to the priest, when the Japanese did get around to MOEN, they made rapid progress.

The lighthouse on the east tip of MOEN was erected in 1937, the priest said, and the airfields were built in 1939. It was in 1940 that the main force of the Japanese Navy came to TRUK, and the Army arrived in 1943.

Coincident with the expansion of the military installations at TRUK, in 1940 the Japanese stopped all communication between the missionaries and their homes. Henceforth, TRUK"was to be isolated. Until 1940, the missionaries had been free to go from island to Island as they pleased. About the latter part of 1940, how­ever, they were restricted to one island.

Japan's successive reverses in the Pacific, i.e., TARAWA, KWAJALEIN, SAIPAN, GUAM, etc., resulted in an emphasis being placed on AT warfare at TRUK. Strong and persistent delaying actions were to be the order of the day, Instead of the previous tactics of counter-attacking enemy beachheads. Another lesson driven home by the previous defeats was the necessity for constructing strong positions among rocky cliffs in order to be able to withstand artillery bombardments. Be­cause of the severance of supply lineo (with the loss of SAIPAN) steps were taken to make TRUK self-sufficient. To this end, all land was put under cultivation, and sweet potatoes became the food staple.

The Army at TRUK felt that it could repel an American attack for a very long period, assuming that ten American divisions were brought against it. The Navy was not so optimistic, feeling that three months would be the time during which it could hold out. All resolved to die in their places in order to inflict as many casualties upon the enemy and gain as much time as possible. It does not appear that the Japanese ever felt that they could permanently hold TRUK.

Although the TRUK garrison lacked adequate quantities of planes, anti-aircraft and heavy artillery, ammunition, fortress-construction units, and materials for such construction, they stated that they were well satisfied with their overall situation—apparently feeling that the lack in material could be countered by the spirit and determination of all the men. The morale of the Japanese on TRUK was, at all times, very high, it was stated.

The TRUK garrison received information concerning the activities of the UNITED STATES forces from the Imperial Headquarters. However, it appears that the com­plete story of Japanese Naval reverses was not forthcoming from TOKYO. Any in­formation received from TOKYO was considered to be reliable. Such news as the Japanese on TRUK received from UNITED STATES broadcasts was not wholly ignored— neither was it believed. The Japanese did not place too much credence in these broadcasts, as they considered them to be propaganda. Such information was "Put aside for reference".

The Japanese on TRUK correctly estimated that the U. S. forces would attack SAIPAN and IWO JIMA. It appears that at no time did they anticipate TRUK would be the subject of the next all-out assault. However, at such times as they were under attack by out task-forces, they seemingly felt that this was the forerunner of the invasion attempt. After SAIPAN, they assumed correctly that the weight of U. S. power would fall to the northwest. But they did not know whether FORMOSA, OKINAWA, the CHINA Coast or a combination of the three would be the precursor of the attack on JAPAN. Realization that TRUK had been by-passed came when OKINAWA was attacked, and it was thought that JAPAN proper would be next.

After August, 1944, no ships were able to get to TRUK from the Japanese home­land, and the garrison was completely isolated, save for sporadic visits by sub­marines.

TOTAL STRENGTH. jOFFICERS ENLISTED CIVILIAN PERSONNEL TOTAL

o ARMY 741 13,558 14,299

NAVY 419 9,422 14,220 24,061

TOTALS 1,160 22,980 14,220 38,360

ARMY UNITS ON TRUK. DATE OF

UNIT 31st Army Hq#

LOCATION DUBLON

OFF. 31

W.O. 3

NCO 43

EM 51

TOTAL 128

CODE NAME SONAE 7920

ARRIVAL 20Jan45

ro

52nd Div.Hq. DUBLON 37 10 100 151 298 KASHIWA 4650 4Jan44 z 69th Inf.Regt. DUBLON 124 32 717 1,821 2,694 a 4654 4Jan44

(-2 Bn, 2nd Bn

150th Inf.Regt. Tank Unit

on UMAN) MOEN TOL

109 4

29 2

828 39

1,170 58

2,136 103

«* 4656 4672

18Feb44 18Feb44

CO

<

Signal Unit 9th Ind.Eng.Regt .

DUBLON DUBLON

8 15

1 4

52 145

180 319

241 483

*M 4662 4812

4Jan44 16Apr44

o Transportation DUBLON 3 1 30 71 105 " 4673 18Feb44 Z Unit

Over-sea Trans- DUBLON 32 6 353 741 1,132 * 4674 llMar44 port Unit MOEN

Ordnance Serv. DUBLON 3 2 34 20 59 " 4664 18Feb44 Unit

Intendance Serv. Unit

MOEN FEFAN

15 4 36 62 117 " 4675 18Feb44 z DUBLON

Field Hospital TOL MOEN DUBLON

51 4 176 418 649 " 4676 4Jan44 Q

Z UMAN FEFAN TOL

51st Ind.Mixed UDOT 244 63 1,695 2,786 4,788 SONAE 17564 24Mar44 Brig. TOL 16Apr44

FEFAN PARAM o

11th Ind.Mixed Regt.

FEFAN DUBLON

65 24 420 857 1,366 " 17585 18Sep44 19Jan45

TOTALS 741 185 4,668 8,705 14,299

The 31st Army was organized at TRUK.

The 2nd Detachment arrived on 24 March, 1944 and the 8th Detachment arrived on 16 April, 1944. These units were reorganized as the 51st Independent Mixed Brigade. z

o c/>ui CO

The 51st Independent Mixed Brigade was disposed as follows: Z 336th Ind. Bn. -\ 337th Ind. Bn. - UDOT ui

338th Ind. Bn. y TOL 339th Ind. Bn. -•>__,_.„ lst Art. Unit ( 2nd Art. Unit -)FEFAN 51st 1MB Hq. J 340th Ind. Bn. - FEFAN & PARAM.

UI

Z

The Headquarters and the 1st Battalion of the 11th Independent Mixed Regiment was on FEFAN; the 3rd Battalion was on DUBLON.

JAPANESE ORDER OF BATTLE

STRENGTH AND DISPOSITION OF ARMY FORCES ON TRUK (INCLUDING MEDICAL PERSONNEL). STRENGTH AND DISPOSITION OF NAVY FORCES ON TRUK.

ISLAND OFFICERS W.O. NCO ENLISTED MEN TOTAL CIVILIAN GRAND MOEN 146 29 735 2,052 2,962 UNIT OFF Wt0. NCO EM TOTAL PERSONNEL TOTAL

I cc

FEFAN DUBLON PARAM UMAN

116 227 20 36

38 43 6 10

625 697 127 174

2,135 2,275 212 653

2,914 3,242 365 873

DUBLON ISLAND: 4th Fleet Hq. Judge Advocate

25 2

3 104 2

69 201 4

5 8

206 12

UDOT 28 10 181 529 748 1st Pers. Repl. Dept. 2 5 2 9 9 ULALU 3 0 10 27 40 41st Guard Police 44 19 567 475 1,105 102 1,207 PATA 9 2 49 156 216 4th Comm. Unit 20 2 169 153 344 2 346 N. TOL 41 11 237 538 827 4th Harbor Dept, 4 27 18 49 30 79 S. TOL 81 14 327 911 1,333 TRUK Transport Unit 2 1 6 3 12 46 58 POLLE 35 15 221 503 774 E.CAROLINES Naval Air Unit 9 2 114 110 235 5 240

227th Const. Bn. 4 4 z ARMY MEDICAL PERSONNEL. 4th Naval Stores Dept. 16 4 50 38 108 280 388 MOEN 29 6 85 193 313 4th Naval Const. Unit 8 14 14 36 461 497 DUBLON 45 8 92 193 338 4th Naval Civil Eng.Dept. 7 3 17 8 35 974 1,009 FEFAN 17 1 38 103 159 4th Naval Hospital 11 1 23 42 77 38 115 UMAN 4 0 8 25 37 4th Naval Office of Supply 2 2 4 46 50

CQ UDOT 4 0 10 29 43 and Administration TOL 26 1 47 129 203 104th Naval Air Depot 3 1 3 7 14 190 204 POLLE 2 0 5 15 22 4th Meteorological Unit 1 8 5 14 31 45 O

CL PARAM 2 0 2 13 17 10th FPO Unit 16 16 KJ TOTALS 129 16 287 700 z

KJ NOTE: The T/0 as presented above was obtained from the Japanese Forces TOTALS 156 36 1,111 944 a, 247 2,238 4,485

0

z

at TRUK and no attempt has been made to verify its accuracy.

NAVY UNITS ON TRUK. ETEN ISLAND: CIV. GRAND CODE DATE OF 41st Naval Guard Force 3 1 37 79 120 120

UNIT OFF W.O. NCO EM TOTAL PERS. TOTAL NAME ARRIVAL E.CAROLINES Air Unit 4 4 74 88 170 2 i72 4th Fleet Hq. 28 7 129 76 240 22 262 U 87 10Nov43 4th Naval Civil Eng.Dept. 1 3 4 166 170

CO Q

TOTALS 114 167 294 168 462 4th Fleet Judge Advocate 2 2 4 8 12 Dept.

87 10Nov43 u

uuuuuuuuuuuu

Z 1st Pers.Repl.Dept, 41st Naval Guard Force

2 61 29

5 885

2 9 795 1,770 155

9 1,925

43rd Naval Guard Force 28 13 499 521 1,061 14 1,075

225 Dec42 44 15Nov40 504 lDec44 CO TONELIK ISLAND:

47th Naval Guard Force 44 5 546 908 1,503 8 1,511 603 20Mar45 624 !May45

41st Naval Guard Force 23 41 66 Ul 48th Naval Guard Force 31 13 412 769 1,225 1 1,226 49th Naval Guard Force 21 9 300 294 624 2 626 4th Comm. Unit 24 5 246 228 503 31 534 4th Harbor Duty Dept. 11 1 122 78 212 158 370 TRUK Naval Transp.Dept. 11 2 46 28 87 612 699

Z 625 lMay45 17 14Jan41

NORTHEAST ISLAND; —i

o 418t Naval Guard Force 3 3 6 688 25Aug41

E.CAROLINES Naval Air 50 35 1, 033 864 1,982 23 2,005 Unit

119 Jul42 MOR ISLAND: 453-27 DUBLON 4th Fleet Hq. 1 1 3 5

41st Naval Guard Force 7 5 12 -21 TOTALS 15 11 26

453-53 ETEN 453-222 PARAM

Jul44 227th Const.Bn. 7 9 4 20 864 884 4th Naval Hospital 24 1 43 104 172 96 268 4th Naval Office of 2 2 4 46 50 Admin. & Supply

104th Naval Air Depot 9 2 13 17 41 737 778 4th Meteorological Unit 10th FPO Unit

2 17 10 29 64 37

93 37

389 Mar44 169 59

21Aug42 15Dec40 ELI KANIBU ISLAND;

41st Naval Guard Force 4 2 6 135 May42 6"3 Uun41 SALAT ISLAND: 00 Jan41 41st Naval Guard Force 8 2 10 10

uuu

uuu

Z o CO 4th Const. & Repair 12 24 18 54 826 880

4th Const. Dept. 60 Dec40 OTTA ISLAND: 96 lDec41 41st Naval Guard Force 2 4 6 6 62 15Dec40 146 15May42 FALEU ISLAND:

uuuu

4th Repair Dept. 4th Munition Dept. Z

ui 85th Submarine Baae 4th Naval Stores Dept. 4th Naval Civ.Eng.Dept.

30 20

8 15

100 53

58 17

196 105

1,223 9,293

1,419 9,398

41st Naval Guard Force 10 20 31 31

CO UJ

TOTALS 419 145 4,486 4,791 9,841 14,220 24,061 FALO ISLAND: 47th Naval Guard Force 16 3 20 20

Z The 43rd, 47th, 48th and 49th Naval Guard Forces were all formed on TRUK. FALAS ISLAND:

The 4th Naval Base was established at TRUK in August, 1941. Until May, 1944, the 4th Fleet Headquarters commanded the 4th Naval Base; the 4th Naval Base, in turn, commanded TRUK. When the 4th Naval Base was disbanded, in May, 1944, the 4th Fleet Headquarters directly commanded TRUK.

41st Naval Guard Force

FANUELA ISLAND; 41st Naval Guard Force

5

5

5

5

5

5

66

6

10

JAPANESE ORDER OF BATTLE -\ i—i

CIVILIAN GRAND CIVILIAN GRAND UNIT OFF W.O. NCO EM TOTAL PERSONNEL TOTAL UNIT OFF W.O. NCO EM TOTAL PERSONNEL TOTAL

MOEN ISLAND: 47th Naval Guard Force 4th Comm. Unit 4th Naval Harbor Duty Unit E.CAROLINES Naval Air Unit 4th Naval Stores Dept. 4th Naval Civil Eng. Dept. 4th Naval Hospital 104th Naval Air Depot 10th FPO Unit

43 2

30 2 3 4 6

5

1 23 1 3

1

530 32 13 664 11 8 4 10

905 27 13

464

2 18 10

1,483 61 27

1,181 14 16 26 27

8 14 27 15 99

2,145 21 547 7

1,491 75 54

1,196 113

2,161 47 574 7

TOL ISLAND: PATA. POLLE: 4th Fleet Hq.4th Naval Guard Force43rd Naval Guard ForceTRUK Transport UnitE.CAROLINES Naval Air Group227th Const. Bn.4th Naval Stores Dept,4th Civil Eng. Dept,4th Naval Const. Unit

1 1

22 9 2 7 4 5 2

2 11 1

3 5

61 397 40 24 9 20 12 2

38 404 25 27 4 2 2 1

1 102 834 75 53 20 29 24 5

2 14 566

860 410

2,889 220

2,

1 104 848 641 53 880 439 913 225

o

I

in

TOTALS 90 34 1,272 1 ,439 2,835 2,883 5,718 4th Naval Hospital 4th Meteorological Unit

4

1 6 9

16 5

26 15

28 33

54 48

CO

10th FPO Unit 14 14 z BUET ISLAND: TOTALS 58 22 580 524 1.184 5,036 6, 220 41st Naval Guard Force 4 1 5 5 ULALU ISLAND:

4th Comm. Unit 1 2 23 27 53 15 68

FEFAN ISLAND: 4th Fleet Hq. 2 3 19 1 25 10 35

4th Civil Eng. Dept. TOTALS 1 2 23 27 53

227 242

227 295 CQ

< 41st Naval Guard Force 48th Naval Guard Force 4th Harbor Duty Unit E.CAROLINES Naval Air Group 4th Naval Stores Dept. 4th Naval Construction

3 18

5 2

3 11

51 264

31 11 8

82 437

50 17 3

139 730

81 33 13

1 11

174 145

139 731 11 81 207 158

UDOT ISLAND: 4th Fleet Hq. 43rd Naval Guard Force 48th Naval Guard Force 4th Naval Stores Dept. 4th Civil Eng. Dept.

3 4 1 2

2

1

5 40 35 3 3

5 28 77

1

10 73 116 4 7

5

21 789

15 73 116 25 796

o CL.

z

4th Civil Eng. Dept. 4th Naval Hospital

TOTALS 3 35

1

18

4 6

394

2 15 607

9 24

1,054

1,169 8

1,518

1,178 32

2,572 FALA-BEGUETS.ISLAND:

TOTALS 10 3 86 111 210 815 1, 025 < &.

4th Naval Stores Dept. 2 4 1 7 239 246 z

PARAM ISLAND: 48th Naval Guard Force E CAROLINES Naval Air Group 4th Civil Eng. Dept,

9 5 1

2 5

113 103 2

255 116 1

379 229 4

1 214

379 230 218

EOT ISLAND: 41st Naval Guard Force 43rd Naval Guard Force

TOTALS3 3

58 58

1 82 83

1 143 144

24

24

25 143 168

CO

Q

Z

TOTALS 15 7 218 372 612 215 827 OLLAN ISLAND: 43rd Naval Guard Force. 2 4 6 6

co Ul

Z TSIS ISLAND: E.CAROLINES Naval Air Group 11 3 14 14

YAWATA ISLAND: 43rd Naval Guard Force. 2 3 5 5 o

4th Civil Eng. Det>t. TOTALS 11 3 14

125 125

125 139 SUB-TOTALS FOR ABOVE 410 141 4,349 4, 729 9,629 14,150 23, 779

<

SHIP-BASED PERSONNEL NAME: 41st NAVAL GUARD UNIT: O Light Mine Layer #3 3 1 41 10 55 55

TARIK ISLAND: 4th Civil Eng. Dept, 7 7

Special Mineswpr##5 Fuyo Maru #2 Hosai Maru #2 Kosei Maru Hozan Maru

2

1 1

2 1

30 10 6 10

13 9 6 4

47 20 13 15

1 1 2 7

47 21 14 17 7 z

Yamato Maru #5 1 1 7 8 o TOTALS 7 4 98 42 151 18 169

UJ CO

UMAN ISLAND: 49th Naval Guard Force 21 9 300 294 624 2 626

4th NAVAL HARBOR DUTY: Futakami, FEFAN Tug #3, FEFAN

2 37 1

18 57 1 13

57 14

Z UJ LU

4th Comm. Unit 1 1 22 21 45 45 Manshu Maru, DUBLON 11 11 UJ

4th Harbor Duty Unit E.CAROLINES Naval Air Group 4th Civil Eng. Dept, 4th Naval Hospital

5

2

1 1

43 12 4 4

27 6 1

13

75 19 6 19

38

588 1

113 19 594 20

Dai shin Maru, DUBLON Kotobuki Maru, DUBLON Yachiyo Maru, MOEN Shinzo, Maru, MOEN

1 2 3 7 5 10 6

7 8 10 6

UJ CO UJ

Z TOTALS 29 12 385 362 788 629 1,417 TOTALS 2 39 20 61 52 113

SUBTOTALS 9 4 137 62 212 70 282 ELIKANIBU ISLAND: 4th Naval Stores Dept, 1 1 1 GRAND - TOTALS 419 145 4,486 4, 791 9,841 14,220 24, 061

ii

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

ng~the planning stage of this report, prior to the arrival of the Study below. Each photograph, within the panoramic strips, is numbered and is represented Group at TRUK, the decision was made to supplement the written report by the maximum on the map by a numbered ray from the lettered panoramic station, thereby enabling use of photography, thereby visually presenting the exlstant conditions and subjects the reader to rapidly and accurately visualize the area covered by each photograph. of Interest. In addition to the treatment of specific subjects by this means, the decision was made that a series of panoramic photographic strips from critical ele- Panoramic strips from Stations "C", "D", "E", "F", and "I" each have 360° cov­vations should be prepared to facilitate the presentation of the terrain and asso- erage. The panoramic strips from Stations "A", "B "G". "H«, and "J" have 185°, ciated features. 120°, 270°, 300°, and 170° coverage, respectively, due to obstructed views.

Panoramic strips were photographed on various Islands as indicated: three on The numbers of the individual photographs contained In the panoramic strips are MOEN, three on DUBLON, two on FEFAN, one on UMAN, and one on PARAM. These are pre- preceeded by an abbreviation, "PMM, which Indicates the basic number of a picture sented on the following pages. In order to assist the reader in orienting the pan- whether on the Outline Map (Figure 3 - PANORAMIC PHOTOGRAPHIC STATIONS), In APPENDIX

X oramic strips and individual pictures contained therein, a map (Figure No. 3 ) , lo- III (Ground Photographic Reference Data), or on the map entitled "LOCATION OF GROUND cating the camera stations from which the panoramic strips were taken, is presented PHOTOGRAPHS" in PART TWO. Sea "COMMENT Oil THE NUMBERING OF PHOTOGRAPHS" on page iv.

116,117

115

365 363

366

MAN IS.

DUBLON IS. ETEN IS. 367 FALO IS

o 361

z 368

[STATION V

51 135

134 CO a z

CO 275,276

274 372

o 371

272

o

*: oc I—

Z TSIS IS.

o CO LU CO

z 433 434

EASTERN ISLANDS OF TRUK ATOLL CO ELEVATIONS LU 435 STATION — ELEVATION Z MAP REFERENCE - H.O. CHART NO. 6048 "A" A'SfVf APPPDY )

SCALE ­ |: 55,600 "B" — M C " —

— 45O'(APPROXJ — 754'

"D" — 85 31

"E M —- — 3901

— 1184'

441 V — 958'

440 439 TAR K IS. V — II. II

1 ——

2361

8991

FIGURE NO. 3-PANORAMIC PHOTOGRAPHIC STATIONS 7°20'N v— 880*

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

T I P O F F A L O I S L A N D O U T E R R E E F L I G H T H O U S E RAD 10 S T A T I O N HILL 810 SOUTH RIDGE OF HILL 1200

I 1 K

.4,

PM 293 PM 292 PM 291 PM 290 PM 289

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "A" MOEN ISLAND

HILL 1200 ANCHORAGE MANGROVE SWAMP H LL 700 (STATION "C") HQS. , I S.COM.(21ST.MAR)

o a.

Z

£ Z v-/

CO QZ

CO

LU

Z _ i

CAUSEWAY r o

o

z o en LU CO

z

LU

Z

PM PM 285 PM 286 PM 287 PM 288

PANORAMIC PHOTOGRAPHIC STRIP FRQM STATION "B'VMOEN ISLAND

n^Jr

WWL 13

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

H Q S . , CAUSEWAY LIGHTHOUSE H ILL 800 C . G . Q U A R T E R S , T R U K A T O L L F E F A N I S L A N D P A R A M I S L A N D F L O A T I N G C R A N E

S M A L L B O A T P I E R N . C . B . C A M P i H I L L 1 2 0 0 o

o

I

5 m

CO

Z

O3

o Q_

z

z PM 278 PM 279 : v . PM 268 & 281 PM 269 PM 270

CO Q PANORAMIC PHOTOGRAPHIC STRIP f ROM STATION 4ICM MOEN ISLAND CONTINUED z

o O U T E R R E E F R O A D A C R O S S C A U S E W A Y H I L L 3 9 0 ( S T A T I O N " E " ) S I G N A L L I G H T ( S T A T I O N " F " ) F E F A N I S L A N D

on R A D 10 S T A T I O N

Z o (/> CO

Z

Z a. <

/ \ 137 PM 138 PM 139 PM 1U0 PM 143 PM 141

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION UD"DUBLON ISLAND CONTINUED

14

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY IE O L I S L A N D U . S . N . A N C H O R A G E L . S . T . L A N D I N G S A I R F I E L D U N D E R C O N S T R U C T I O N F O R U . S . N . FALO ISLAND

o a.

Z

PM 2 7 1 PM 272 PM 273 PM 274 PM 275 PM 276 PM 277 Z

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "C" MOEN ISLAND Q

Z

M T . N I S H I K I . ( S T A T I O N " I " ) , F E F A N I S L A N D U D O T

P A R A M I S L A N D T O L I S L A N D

I S L A N D A N C H O R A G E S E A P L A N E B A S E H I L L 1 2 0 0 t M 0 . E N

H I L L

I S L A N D

8 0 0 . M O E N

R A D I O

I S L A N D

S T A T I O N

CO

LU

Z —i

o

z o en LU CO

Z UJ

CO LU

Z

P M 1 4 3 | P M 1 4 2 PM 133 PM 134 PM 135 PM 136

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION MD" MOEN ISLAND

15

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

U M A N I S L A N D E A T O N I S L A N D F E F A N I S L A N D ( A I R F I E L D )

F U E L P I E R

o

I

en Z

Z

PM 1 1 5 PM 116 & 117 PM 118 PM 119 PM 120 PM 121 PM 122 z

m

to Q Z

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION UE" DUBLON ISLAND CONTINUED

z -I

o a:

E T E N I S L A N D ( A I R F I E L D ) U M A N I S L A N D F E F A N I S L A N D M T . N I S H I K I ( S T A T I O N " I " ) T O L I S L A N D _ ­ .

SEAPLANE BASE \

A M M U N I T I O N , T O R P E D O S T O R A G E F L O A T I N G D R Y D O C K

o

z O CO ui to

zu. 1 Q U£ CO

PM 153

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "F* DUBLON ISLAND CONTINUED

16

^ •1

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY. f

S E A P L A N E B A S E S I G N A L L I G H T ( S T A T I O N " F " ) S I G N A L T O W E R ( S T A T I O N " D " ) M O E N I S L A N D L I G H T H O U S E ( M O E N I S L A N D )

F E F A N I S L A N D \ H O S P I T A L A R M Y R A D I O S T A T I O N

PM 122 PM 123 I PM 110 PM 1 1 1 PM 1 1 2 PiV, 1 1 3 P M 1 1 4 PM 1 1 5

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "EMDUBLON ISLAND

A N T I - T A N K B A R R I E R S S E A P L A N E B A S E M O E N I S L A N D S I G N A L T O W E R ( S T A T I O N " D " ) N E . P O I N T OF D U B L O N I S L A N D S E . P O I N T O F D U B L C N I S L A N D

A N C H O R A G E R A D I O S T A T I O N L I G H T H O U S E O U T E R R E E F H I L L 3 9 0 ( S T A T I O N " E " )

P M 1 5 5 PM 1 5 4 PM PM 1 4 5 PM 1 4 6 PM 147

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION MF" DUBLON ISLAND

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

F E F A N I S L A N D R A D I O S T A T I O N M O E N I S L A N D S T A T I O N " F W , D U B L O N I S L A N D OUTER REEF

t TEN I S L A N D

z

o CL

z

PM 369 PM 36 1 j PM 362 PM 363 PM 364 z

z PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "G" UMAN ISLAND CONTINUED

UJ z - J

o S T A T I O N " D " t D U B L Q N I S L A N D S T A T I O N " F " . D U B L O N I S L A N D F E F A N I S L A N D T S I S I S L A N D as <

O

z O CO UJ

in UJ

z

P M 4 3 3 P M 4 3 4 P M 4 3 5 P M 4 3 6

i ta-PANORAMIC PHOTOGRAPHIC STRIP FROM STATION *H" PARAM ISLAND CONTINUED

18

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

SMALL BOAT DOCK F A N E U I S L A N D O U T E R R E E F I S L A N D S

o T—

I

m

Z H­LU _J - I

O o. Z

PM 364 PM 365 PM 366 PM 367 PM 368 Z

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION " 6 " UMAN ISLAND CO QZ

CO

S M A L L B O A T D O C KI

T A R IKI

I S L A N D P A R A M A I R F I E L D T O L I S L A N Dr E I O L I S L A N D U D O T I S L A N D o OS

Z o CO tu CO

z

CO

Z

PM 437 PM 439 PM 440 PM PM 442

CONTINUED PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "H" PARAM ISLAND

19

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY

UMAN SLAND MT. UBUN TSIS ISLAND T A R I K I S L A N D T O L I S L A N D U D O T I S L A N D

PARAM ISLAND

z

o OL

z

PM 378 PM 379 PM 380 PM 381 PM 375 PM 376 PM 377 z

Z PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "P FEFAN ISLAND CONTINUED CO

UJ

z —I

o

P i c t u r e N o . i (PM 5 7 2 ) DUBLON: S e e n f r o m p o i n t i £ m i l e o f f s h o r e , t r u e - s o u t h . P a r t of MOEN may b e s e e n i n t h e l e f t b a c k q r o u n d .

z o (/I

CO UJ Picture Mo. 2 (PM 571) UMAN: Depicted from position i£ Z mtle offshore to the south. Mt. URORAS is shown in the

center of the photograph. JACK STAFF-AV.R 35

For Information regarding the system used in the numbering of individual photographs, of which the above individual photographs (Nos. 1 & 2) are the first to appear in this report out of a total of 351, see "COM­MENT ON THE NUMBERING OF PHOTOGRAPHS'1 on page iv.

A PANORAMIC PHOTOGRAPHIC TERRAIN STUDY ? ' I f f /

MT.SANREI A N C H 0 R A 6 E S E A P L A N E B A S E MOEN I S L A N D L I G H T H O U S E S T A T I O N " D H t D U B L O N I S L A N D S E A P L A N E B A S E E T E N I S L A N D A / F

F L O A T I N G D R Y D O C K S T A T I O N " F " / O U T E R R E E F

z

PM 369 & 3 8 1

CONTINUED

PM 370 PM 3 7 1 PM 3 7 2

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION "P FEFAN ISLAND

PM 3 7 3 PM 37U KJ

z

CO QZ

to

S I G N A L T O W E R . D U B L O N

F L O A T I N G

I S . . ( S T A T I O N " D " ) S E A P L A N E

D R Y D O C K S T A T I O N " F " ( S I G N A L L I G H T )

B A S E E T E N I S . A I R F I E L D O U T E R R E E F U M A N I S L A N D MT. ARASHI TSIS ISLAND O

z o CO UJ CO

Z

CO UJ

Z

PM 387 PM 386 PM 385 PM 384 PM 383 PM 382

PANORAMIC PHOTOGRAPHIC STRIP FROM STATION M J " FEFAN ISLAND

21

ARTILLERY AND ORDNANCE

Final Defense Location CO o The Information appearing herein was obtained from sources as follows: En

Conferences with Japanese Army and Navy Staff Officers. CO W

Copies of defense plans furnished by the Japanese. B WX Actual reconnaissance with Japanese authorities covering all of the

•H M PQ

Iprincipal Islands within the TRUK Atoll and the reef islands at NORTH and SOUTH O <D

Passages. This reconnaissance included visits to praotically all battery positions O 05 Omounting guns of 8cm or larger, and about 40 percent of positions which had mounted ITEM B £42 field and mountain artillery. The reconnaissance .was more than adequate to establish m the fact that the data furnished by the Japanese was accurate, NAVY

20cm Guns. 4 4 1 946 4 DEVELOPMENT OF THE DEFENSES. 15,5cm Guns. 3 3 1 773 3

15cm Guns. 28 25 12 7,144 9 2 Information as to the early development of TRUK was not easily obtainable. 14cm Guns. 0 6 3 3,855 2 4

Consideration of the information obtained throughout the visit of the group to TRUK 12.7cm Guns AA (dual 2 2 1 2,908 leads to the conclusion that comparatively little progress had been made either as mount). to fleet base facilities or as to fortifications prior to 1940. Naval construction 12cm Guns, CD. 6 6 6 2,780 1 and supply units arrived in 1940. The 4th Naval Base Unit was organized In August 12cm Guns, DP. 29 29 9 1,957 11 1 6 4 1941. The 4th Naval Defense Unit, strength about 850, was organized on DUBLON on 8cm Guns, CD. 609 15 November 1941. The 4th Fleet Headquarters, organized at SAIPAN in November 1939, 8cm Guns, DP. 4 2 1 2,122 was moved to TRUK in November 1943. The 52nd Division arrived at TRUK beginning in 75mm, AA, Type 88. 9 8 2 3,237 4O January 1944. The 4th Fleet abandoned TRUK in February 1944. Such heavy armament 25mm, Mult mount, MG, 73

CL as might have been emplaced prior to arrival of the 52nd Division was mostly above Type 96, 472,835 ground and was in positions on reefs as well as larger interior islands. Following 25mm, single mount, MG, 23 z our air raids of February 1944 and departure of the 4th Fleet, the defense plan was Type 96. changed in that heavy artillery was withdrawn from the reef islands to the inner 20mm, MG, Type 99 MKI. 91 47,207 islands, and artillery on the inner islands, excepting certain anti-aircraft 13mm, MG. 115 265,064 batteries and turreted seacoast batteries, was placed underground. This program of Range Finder (4.5m, 8 digging in was delayed by lack of equipment, cement, and explosives. It had not 3.5m, 2.5m).

z been entirely completed when peace was declared. Range Finder, 1.5m. 7 Director Type 2. 1 3 Director Type 95. 2 1CO EQUIPMENT AVAILABLE. Searchlights under 6 6 1

Z 110cm. The following tabulation shows the quantity of principal weapons, ammunition, Searchlights 110cm to 14 14 4 1

and fire control equipment; and the disposition of the weapons by islands under the 150cm. CO defense plan Initiated in 1944: Searchlight Controllers. 2 1 Ul

Legend: A - Guns per Jap Inventory. ARTILLERY TACTICAL CONTROL. Z B - Guns per reconnaissance and Jap plans. C - Rounds of ammunition, all types wap Inventory). The seacoast and anti-aircraft artillery was supplied and manned almost entirely o by the Navy. Field and mountain artillery was furnished and manned by the Army.

(DC Dispositions were determined by coordination and agreement between Army and Navy authorities. Dispositions In the final defense plan were designed for a rigid fixed defense of the mine fields located at entrances to and within the lagoon, and to rigid inshore defense of the inner islands. So far as was consistent with this plan, Final Defense Location artillery on the various Islands was to be capable of mutual support. Under the

CQ general defense plan for the atoll as a whole, separate Navy and Army Commanders were designated for each of the principal islands. Each Naval Commander controlled

to his own units under the plan until he was no longer capable of performing his • mission, then the remnants were to come under Army control. General fire direction

22 CO M M go o of heavy artillery was exercised at the 4th Fleet and 31st Army Command Posts on qw ti a< w DUBLON. Communication with island command posts was maintained by means of sub­

M0E

1

Z aE-« H iJ S3 mwB<« 8ooi

2ffl C marine telephone and telegraph cable, radio, visual signals and pigeons. General ITEM A B ^ O O O search radar was available for surface and air targets and was reported to be sat-O Ck«8 W &* E* o isfactory as to results. For details see communications section In this report.

CO ARMY Ul CO ARTILLERY FIRE CONTROL.

All types of seacoast and anti-aircraft heavy artillery were very weak in fire

Z Ul 105mm Army Howitzer. 6 6 1 007 6 u. 8cm Armstrong Gun (CD). 7 7 7 I: 341 2 2 3 Ul 8 11 306 2 9475mm, AA', Type 88. control equipment. There was no fire control radar. The number of range or height

finder8 available was sufficient to equip but a few batteries. Only four anti-air­2,Q

Ul 34 34 727 3 834 675mm Mtn. Gun, Type 41. 4 2 1 10 10, 46 48 40 540 17 11 575mm Mtn. Gun, Type 94 CO Ul

2 2 2 9 craft directors were available. Anti-aircraft batteries not equipped with directors and 75mm Field Gun and associated data transmission systems had to rely on improvised forward area

type sights. In the case of seacoast artillery reliance was placed principally on registration on markers and buoys at known ranges. Horizontal base observation and plotting or prediction systems were not employed. The Japanese reported that

Z Type 38 & 95. Heavy Range Finder, 2

8yr Type. Field Range Finder, 30 much fire control equipment had been lost enroute to TRUK. Field artillery generally

Type 93. was equipped with standard panoramic or telescopic sights.

22

ARTILLERY AND ORDNANCE Wi *w

ARTILLERY - GENERAL REMARKS.

The long range artillery defense of TRUK was weak. Batteries capable of firing effectively beyond the reef line were limited to one turreted 4-gun 20cm. (811) bat­tery located on DUBLON, and to one turreted 3-gun 155mm. (611) battery located on UMAN. The remaining heavy artillery, all of 15cm. or less, was capable only of mine field and inshore defense.

The entire searchlight defense of TRUK employed only 20 searchlights. Only 4 of these lights employed control stations and no searchlights employed radar control* The majority of the searchlights were available for use by both anti­aircraft and seacoast artillery. Little attempt was made to control searchlights tactically from the Naval CP on DUBLON, tactical control usually resting with the battery commander of the nearest gun battery. In general, the searchlight defense of TRUK was exceptionally weak.

Although our air action had effected practically complete destruction of above-ground naval and air installations, no damage was sustained by turreted or other heavy artillery in open emplacements, excepting one anti-aircraft gun battery on ETEN consisting of two 12.7cm. twin mounts which were destroyed.

Naval bombardment by the British for two days, about 27 June 1945, resulted in no damage to heavy artillery.

ARTILLERY POSITIONS ON BARRIER REEF ISLANDS.

Artillery and searchlights located on the reef islands were moved after February 1944, to cave positions on the principal islands Inside the reef. Artillery and searchlights had been emplaced as follows:

ISLANDS GUNS

NUMBER SIZE FIELD

OF FIRE SEARCHLIGHTS NUMBER SIZE

TONELIK Northeast

MOB

SALAT

OTTA

FALEU FALASIT ELI KANIBU YAWATA

2 in turret 2

2

2

2

2 2 2 2

14cm. 15cm.

15cm.

15cm.

15cm.

15cm. 15cm. 15cm. 15cm.

270° to 90° T 360°, except for small area blanked by palm tree8. Water area outside reef. Water area outside reef. Water area outside reef. 360° __ __ —

1 —

1

1

1

1

—

90 cm. —

90cm.

75cm.

75cm.

90cm. K B

—

Direct fire telescopic sights were employed with all weapons. At TONELIK and FALEU Islands 2.5 meter range finders were employed and at approximately one half of the other islands 1.5 meter range finders were employed. The Navy controlled all batteries located on the reef islands and communication was maintained between DUBIXJN and all islands by use of underwater telephone and telegraph cable and radio. Positions were of the open type with log and sand parapets. Gun pedestals were bolted to reinforced concrete platforms.

The searchlights were employed primarily for illumination of sea borne targets and secondarily as pick up lights for illumination of aircraft. The lights were emplaoed on small towers approximately 61 high. The lights at TONELIK and FALEU were equipped with sound locators and comparators, and were tactically controlled by searchlight officers; all other lights employed hand control only and were tactically controlled by the battery commanders of the island gun battery. No attempt was made to control the searchlights from the Navy CP on DUBLON.

DESCRIPTION OF INDIVIDUAL BATTERIES.

Maximum and minimum effective ranges were obtained for the Navy weapons by questioning the Japanese battery and battalion commanders and from maps (believed to be quite accurate) submitted by the Jap Navy Headquarters Staff; those for the Army were obtained from Army sources similar to the above Navy sources and also from knowledge of the characteristics of the weapon (characteristics obtained from CINCPAC - CINCPOA Bulletin No. 152-45, 1 July 1945). Limiting angles of fields of fire were obtained for practically all of the Navy emplacements and about 40# of the Army emplacements by actual measurement and for the remaining emplacements from the maps submitted by the Japanese*

At all batteries personnel were quartered in barracks or shacks made of scrap lumber and galvanized sheet metal. These huts varied in size allowing in most cases accomodation of squads and in a few cases accomodation of 150 men. These in addition to galleys, mess halls, and officers quarters, were located in camouflaged defiladed o areas adjacent to the gun positions. During bombing attacks personnel lived in the

ocaves and tunnels of the gun positions* I

Ammunition was stored in the emplacement near each gun with exoeption of one or two batteries on TOL and the 12.7cm AA battery on DUBLON. At these excepted oc positions ammunition was stored both in metal ready boxes placed in niches of the cave or revetment near the gun and in well constructed dumps for reserve ammunition. In almost all caves and tunnels temperatures were moderate and stable. However, the atmosphere was quite humid and in many cases water dripped from the walls and was not well drained from the emplacement. Generally, ammunition storage facilities were very poor.

Intra-battery tactical communication systems consisted principally of telephone circuits employing sound powered or battery powered telephones. Phones were installed at guns, directors, range or height finders, OP1s and CP's in the AA batteries and at guns, range finders, OP's and CP1s in the coast defense and field artillery gun positions. At many of the battery positions the telephone circuits were paralleled with voice tube8 and buzzer systems. The communlcation listed in description of Individual batteries refers to intra-battery type.

OCommunication between gun batteries and the island artillery tactical commanders,

both Army and Navy, was by means of telephone and radio principally and augmented a. by runner and pigeon. Little emphasis was placed on maintaining this communication. z

In the following table, position numbers refer to Figures 4 through 10 (artillery and searchlight positions). The letter prefix denotes the island in accordance with the following code; M-MOEN, D-DUBLON, F-FEFAN, U-UMAN, E-EOT, UD-UDOT, P-PARAM, T-TOL.

Z

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Picture Mo. 3 (PM 486) FORMER 14cm GUM EMPLACEMENT, FALEU ISLAMD (Reef).

23

ARTILLERY AND ORDNANCE

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M-l 1 75mm.Mtn.Gun, A Cave* Direct Fire. 8,000 No M-16 1 8cm.Armstrong A Open revetment. Direct; Fire* 8,000 No

M-2T.94

1 75mm.Mtn.Gun, A Cave. Direct Fire. 900

8,000 No M-17 1type Gun.

75mm.Mtn.Gun, A Cave w/palm log Direct Fire sights; Yes T.94 T.94 embr. Elev. no communication.

z M-3 1 75mm.Mtn*Gun,

T.94 A 3 caves con­

nected. Direct Fire. 8,000

900 No

M-18 2 75mm.Mtn.Gun, A -15° to / 40°. Cut type revet- Direct Fire sights; Yes

LU _J _J

(8,000)NE (1,300) (8,000)SE

M-19 1T.94

8cm.CD.Gun,3rdyr. type.

A ment. no communication. Palm log cut & Direct Fire sights; cover type cave no communication.

Yes 16 & 17

OQ M-4 1 15cm.,40 cal.Armstrong Gun.

N Cave w/gravel filled 55 gal.

Direct Fire;tele­scopic sights;

( 700) 10,900 1,200

Yes M-20 1 12cm.CD.Gun,3rd N

w/concrete embr. Elev.-2oto/5°. Concrete cut & Direct Fire sights; 16,500 Yes 11 & 12

O (Some instruc­tion plates on

drum embr.Elev.-telephone & voice 4° to / 20°. tube.

yr. type* cover w/concrete noembr* Elev*

communication. 900

a. gun in Spanish). -7° to / 28°. Z

G M-5 1 15cm.,45 cal.

Vickers(B*L.G. Mk H) Gun.

N Cave w/gravel filled 55 gal. drum embr.Elev -7° to / 18°.

Direct Fire;tele­scopic sights; RF for use of guns at positions No.M-5 & M-6,also,which are all connected by

15,400 1,200

Yes M-21 4 20cm.,40 cal*Armstrong Tur­ret type Gun ­removed from Jap cruisers IWAMI, IWATE,NISSIN,'

N Turrets in open Azimuth & eleva­revetments*Elev. tion telescopes on -5° to / 28°. each side of gun;

4.5m.RF;oil gears were on each gun, to move it in ele­

19,800 1,540

Yes 4 thru 10, & #40

telephone. KASUGA. vation & azimuth; M-6 1 15cm.,45 cal*

Vickers Gun. N Concrete cover- Direct Fire;tele­

ed & lined(cut &scopic sights;tele­15,4001,200

Yes telephone & voice tube.

o z

z

o OS < KJ

M-7

M-8

M-9

1 75mm.Mtn*Gun,T.94

1 75mm.Mtn.Gun,T.94

1 75mm.Mtn.Gun,T.94

2 14cm.,50 cal*3rd yr.turret type gun*

A

A

A

N

fill type).Elev.phone & voice -7° to / 18°. tubes. Cave. Direct Fire.

Cave.

Cave.

Caves w/con­crete embrs*

Direct Fire.

Direct Fire.

Direct Fire;tele­scopic sights; 3.5m.BF in CP be­

8,000 300

8,000 660

8,000 400

18,700 1,000

No

No

No

Yes

M-22

M-23

M-24

1

2

1

15cm.,40 cal*Naval Gun*

15cm.,45 cal*Naval Guns*

15cm.,40 cal*Naval Guns.

N

N

N

Cave w/concrete Direct Fire sights; embr. Elev* -4° to / 10°. Cave. Elev. -2° to / 20°.

no communication*

Direct Fire sight; 1.5m.RF; voice tube. Direct Fire sights; 4*5m.RF;no oom­

Cave.Elev.-2 ° to/20°. Another gun of this type muni cat ion. on hand& was to have been em­

10,900 900

15,400 1,100

12,000 1,000

Yes

Yes

Yes

13,14,15

M-ll 4 75mm.AA guns,T.88

N Earth revet­ment Army guns fired by Navy

tween guns;tele­phone & voice tube s• Direct Fire;3.5m, HF;telephones.

Yes

M-25 5 12cm.DP.Guns, N 10th yr.type. Used forAAfire.

placed. Open revetment. None other than Elev. ? to /750 , Btry.Comdr. spot­

ting with 8cm.bin­oculars & calling directions to the

Yes

Z o</> UJ enZ ui u. UJ O LU to LU

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M-12

M-13

M-14

U-15

1 75mm.Mtn.Gun,T.94

1 75mm.Mtn*Gun,T.41

1 75mm.Mtn*Gun,T.41

1 75mm.Mtn*Gun,T.94

A

A

A

A

personnel. Cave* Direct Fire.

Cave w/palm log Direct Fire sights embr. Elev. with known refer­-10° to / 40°. ence points In

field of fire; no communication.

Cavo w/palm log Direct Fire sights; embr. Elev. no communication. -15° to / 40°. Cave w/concrete Direct Fire sights & steel embr. & lm.RF; no comm. Elev .-15°t o/40°. Alternate posi­tion in a cave 50 yds.W.to give field of fire 295° to 20°*

8,000 450

No

Yes

Yes

Yes 18

M-26

M-27

M-28

1

1

4

75mm.Mtn.Gun,T.94

75mm.Mtn.Gun,T.94

12cm.DP.Guns,T.10

A

A

N

guns by voice tubes;guns have open type speed ring sights. A Dir­ector & HF.never arrived from Japan.

Cave. Direct Fire.

Cave w/concrete Direct Fire only; embr. Elev. telephone instal­-5° to / 2° led. Guns revetted Speed ring sights AA positions 50 only;complete tele­yds.apart on phone system in-steel sled bases^talled;Btry.QP.5O Elev./3°to/75°. yds N.of center of

Btry.-had B.C*tel­escope; hand wrench fuze cutter.

8,000 800

5,000 300

No

Yes

Yes

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JAPANESE DEFENSES O N TRUK A T O L L , C A R O L I N E I S L A N D S . C I N C P A C - C I N C P O A BULLETIN 3 -46 , 15 M A R C H 1946

ARTILLERY AND ORDNANCE

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M-29 2 12cm.DP,Guns, N Guns,revetted T.10 AA positions 20

yds apart;steel sled bases-no concrete.Elev. 0° to / 75°.

CQ M-30 1 75mm.Mtn.G-un,

T.41 A Cave w/2 embrs.

15 yds.apart; < gun could be

o moved to either opening. Elev.

a. -5° to / 10°. M-31 2 75mm,Mtn,Gun, A Connecting caves

T.94 w/embrs.20 yds. apart & CP .be­tween the embrs Elev.-5°to/10°.

z M-32 1 75mm.Mtn.Gun, T.94

A Cave. Elev.-3° to / 10°.

Speed ring sights only;no telephones installed;Section Chief stood between guns & shouted;hand wrench fuze putter. Direct Fire;lm.RF. 5,000 in S.cave opening; 300 no communication installed;runner only.

Direct Fire; com- 5,000 munication by run- 300 ner.

Direct Fire;no 5,000 telephone instal- 300 led.

Yes D-4 3 75mm.AA Gun, A Each gun in sep- Direct Fire;3m.RF. T.88 arate cave; at W.gun;known ref-

mounts tipped erence points;Bn. forward to per- island CP.was at mit lower angle this position,tel-

Yes of fli*e. Elev.-10°to/5°.Cave

ephone comm.

connected E.& central guns.

D-5 1 75mm.Mtn.Gun, A Cave w/cane Direct Fire;lm.RF. T.94 embr.and steel at CPjtelephone to

doors;cave con- CP. Yes nected to CP.

10m.W.of gun. Elev.-3°W6°.

D-6 2 75mm.AA Gun, A Newly completed Direct Fire;lm.RF.

Yes T.88 cave connecting at S. gun.

guns;guns 20m. apart;cave en­trance 70m.dis-

Yes

Yes

Yes

.INE

IS

L/\

ND

S.

^

M-33 1 75mm.Mtn.Gun, T.94

A Cave• Direct Fire. 8,000 No

D-1 1 75mm.Mtn.Gun, T.41

A Cave w/concrete Direct Fire;tele­erabr;3/8B steel phone to OP. door covering embr. Elev.

Yes D-7 1 75mm.Mtn.Gun,T.94

A

tance on rever­se slope of hill; electric lights installed.Elev. —5° to -/5° Cave. Elev*. Direct Fire;lm.HF. -3° to / 10°. & known reference

points in field of

Yes

D-2 1O -5° to / 13°. fire;telephone to

12cm.CD.Gun, N Concrete lined Direct Fire;tele- 19,800 3rd yr.type caves;1 gun on scopic sights; 3,000

OP.Yes D-8 1 75mm.Mtn.Gun, A Cut & fill-con- Direct Fire;lm.RFv Yes

•» _j

(1914)fitted w/shield.

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0 1 12cm.CD.Gun,

11th yr.type (1922).

Z D-3 2 105mm.How.,T.91 A

(1931).

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each side of speaking tube, hill connected by caves; cave entrance on S. side of hill. Cave also con­nected to OP.on N.side of hill. Elev.-6° to/30°. Open cave in Direct Fire;lm.RF. 11,000 cliff;guns could at W. gun;0P.in be moved to ob- separate cave;tel­tain max.elev., ephone to OP. (45°);cave con­nected guns. Elev.-3sto/9° in cave.

T.94 crete w/earth telephone to OP. cover-2 concrete embrs.firing ports in em­

D-9 2 75mm.Mtn.Gun, A

placements: Elev. -3° to / 36 .

Direct Fire;lm.RF.Cave connected Yes T.94 by tunnel to OP.on hill between

Yes D-lo 1 75mm.Mtn.Gun, A

position D-7. Elev.-5°to/3°. Concrete lined

positions D-7 & D-9; telephone to OP. Direct Fire. Yes

T.41 cave w/concrete embr. Elev.

D-ll 1 8cm.,40 cal.CD. A -5° to / 5°. Cave. Direct Fire;tele­ 4,000 Yes 21

Gun,Armstrong phone to Bn. CP. 200

D-12 1T.,fixed mount. 75mm.Mtn.Gun, A Cave. Direct Fire;tele- Yes T.94-Gun not phone to Btry.CP. emplaced.

26

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ARTILLERY AND ORDNANCE

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D-13 1 8cm.Armstrong A Cave. Direct Fire sights; 8,,000 Yes D-25 1 75mm.Mtn.Gun, A Cave w/steel Direct Fire. 1,500 Yes T.,40 cal.,fix­ telephone to Bn.CP. 200 T.41 embr. & door. ed mount CD.Gun Elev.-2°to/3°. (Believed to be D-26 2 127mm.DP.Gun, N 1 mount bombed Probably had dir- Yes original Arm- T.89-Twin Mount. out Feb.44;l ector. strong Vickers mount bombed out

Z rather than a Mar45;open revet-Jap copy. ments.

U l 1 75mm.Mtn.Gun, A Cave. Direct Fire;tele­ 6,000 D-27 3 75mm.AA.Gun, Open revetment Direct Fire, No T.41 phone between guns T.88 to fire AA;D-27

& to CP. & D-28 same btry. CO D-14 2. 127ram.DP.Gun, N Concrete revet- T.95 Director,(AA) Yes 22,23,24 D-28 1 75mm.AA.Gun, Open revetment Direct Fire, No <

O CL

T.89(1929)-Twln mount.

ment,w/amrao. & T.94,4.5m.Ster­ready chests eoscopic RF;dir­around perimeter;ect fire sights on

25,27 T.88 to fire AA;D-2^ & D-28 same btry.

z director & RF. guns.Two 60kw.gen­on concrete erators for power; F-l 1 75mm.Fld.Gun, A Cave. Direct Fire, 8,800 No blocks above re-data transmission T.95 500

KJ serve ammo.stor-system;speaking F-2 1 75mm.Mtn.Gun, A Cave. Direct Fire< 6,600 No

$ age;3 revetmentstube & telephone for gun mounts & buzzer for fire F-3 2

T.41 75mm.Mtn.Gun, A Cave in rock Direct Fire

500 6,600 Yes

z (3rd gun wassaid to be lost

commands, T.41 cliff.Elev.-2° to /8°.

3,000

on the way from F-4 2 15cm.,40 cal., N Cave in rock Direct Fire;tele­ 10,900 Yes 35 & 36

D-15

D-16

1

1

75mm.Mtn.Gun,T.41

75mm.Mtn.Gun,

A

A

JAPAN to TRUK. Cave.

Cave,finished

Direct Fire.

Direct Fire.w/pan­

4,000

6,000

No

Yes

Guns.Stabili­ment o-Armstrong Puzzuoli,1902. Removed from old

cliff w/conc­rete parapets. Elev.-5°to/10°

scopic sights; l£m. RF;voice tube only,

2,200

T.94 w/concrete & a oramic sights & 100 Battleship KAS-concrete embr; reference points in UGA. tunnel to rear of cave w/palm log re-inforce­

field of fire. F-5

F-6

1

2

8cm.Gun,Arm­strong type.

8cm.DP .Guns,

A

N

Cave.

Concrete revet-

Direct Fire.

Direct Firejtele­

7,700 2,000

No

Yes 29 & 38 o eg

D-17 2 10cm.How.,T.95. A ment. Proposed cave: One cave com­plete w/con-

Direct Fire w/pan­oramic sights:lm.RF.

9,500 150

Yes

F-7 1

10th yr.type.

8cm.Gun,Arm­ A

ted AA poslt­ions.Elev.O0 to /75O. Cave.

scopes; 1 -m. Stereo­scopic RF.

Direct Fire. 7,700 No crete embr; sec­ond partially F-8 1

strong type. 75mm.Fid.Gun, A Cave in rock Direct Fire.

1,800 8,800 Yes

completed. T.95 cliff. Elev. 1,300 D-18 1 75mm.Mtn.Gun,

T.94 A Cave. direct Fire, 8,000

500 No

F-9 6 12cm. DP. Guns, N -3° to / 6°. Revetted AA po- Type 2 Di rec tor w/ Yes 30 thru

Z

D-19 1 15cm.,40 Cal.,T.41 Gun.

N Cave w/concrete Direct Fire & ref­emfcr. erence points in

field of fire; OP

12,000 1,000

Yes 19 10th yr.type w/ fuze cutters*

sitions. Elev. 0° to /75°.

4 -m. s te reoscopic RF;data t ransmis­sion system i n s t a l -led; a l s o speed r i n g

34

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z UJ u. UJ

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D-20

D-21

D-22

D-23

D-24

1

1

1

2

2

75mm.Mtn.Gun, A T.41

75mm.Mtn.Gun, A T.41

75mm.Mtn.Gun, A T.41

lOcm.How.,T.91. A

75mm.Mtn.Gun, A

Cave.

Cave.

Cave.

Cave.

Concrete lined

w/binoculars;tele­phone to OP.

Direct Fire.

Direct Fire.

Direct Fire.

Direct Fire.

Direct Fire;lm.RF.

6,000 500

6,000 500

6,000 500

10,000 1,000

No

No

No

No

Yes

F-10

F-ll

2

l

12cm.CD.Guns,3rd yr.type.

75mm.Mtn.Gxin,T.41

N

A

Caves in rock cliff w/con­crete embrs; caves not con­nected. Elev.

2 caves con­nected by t u n ­ne l i n which t o

s ight s ; t elephones.

Direct Fire;CP l o - 10,900 cated between guns. 3,000

Direct F i re jpan­ oramic s igh t ; lm .

RF.

6,600 600

Yes

Yes

28

T.94 caves;2 guns on at saddle crest; E.side of ter- telephone to OP. rain saddle;1

emplaceweapon.

t h i s

E.-W. tunnel connecting the 2 guns w/embr. on W.side .Elev. -5° to -f 10°.

28

Picture No. 22 (PM 512) 127mm AA GUN, TYPE 89: AA Picture No. 23 (PM 5°9) DIRECTOR, TYPE 95; U s e d i n battery on DOBLON. Position D-14. 12.7cm AA battery on DUBLON. Posit ton D-14

P i c t u r e N o . 2 4 (PM 5 1 1 ) RANGE FINDER, STEREOSCOPIC , 4 . 5 m , TYPE 9 4 : U s e d m 1 2 . 7 c m AA b a t t e r y o n DUBLON. P i p e m l o w e r f o r e g r o u n d c o n t i n u e s up t h r o u g h R a n g e F i n d e r p e d e s t a l a n d a l s o t o p o s i t i o n n e a r D i r e c t o r f o r f i r e c o m m a n d s , P o s i t i o n D - 1 4 .

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P i c t u r e N o . 2 5 (PM 5 1 0 ) 1 2 . 7 c m AA GUN COMMAND P O S T : P i c t u r e N o . 2 6 (PM 4 0 8 ) T Y P I C A L FIELD OF F I R E : 7 5 * » f i e l d P i c t u r e N o . 2 7 (PM 108) 12.7cm AA GUN, TYPE 89: AA O DUBLON. L o w e r f o r e g r o u n d i s e n t r a n e e t o P e r s o n n e l g u n , t y P e 3 8 . P o s i t i o n F - 1 4 . b a t t e r y o n DUBLON. Pos it 1 on D-14. q u a r t e r s . R e s e r v e a m m u n i t i o n d u m p l o c a t e d mb e n e a t h q u a r t e r s . P o s i t i o n D - 1 4 .

c a v e

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Picture No. 28 (PM 409) GUN POSITION IN CAVE Picture No. 29 (PM 417) 8cm, D.P.. 10th YR TYPE GUN: Picture No. 30 (PM 402) 12cm, D.P. 10th YR TYPE GUN, 12cm, 3rd yr type gun, position F-10. In c oncrete AA position F-6. Posit 1 on F-9.

29

ARTILLERY AND ORDNANCE y &••• ESS

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Mm s: 1 H 1 M 1 £« S *-

F-12 1 15cm.,40 cal., N Cave lined w/ Direct Fire w/tele- 9,000 Yes U-6 1 75mm.Mtn.Gun, A Cave. Direct Fire. 6,000 No Gun.Stabilimen- reinforced con- scopic sights;range 1,200 T.41 5

i to-Armstrong crete; concrete to target estimated; U-7 1 75mm. Mtn. Gun-, A Cave. Elev. Direct Fire sighta 8,000 Yes «*» Puzzuoli. embr. Elev. telephone & voice T.94 -3° to /35°.

-5° to /14°. tube to CP. U-8 2 14cm,,50 cal. N Caves connected Direct Fire sights; 18,700 Yes z F-13 1 15cm.,40 cal*, N Cave lined w/ Direct Fire w/tele- 9,000 Yes Gun,3rd yr. Elev.-5Oto/24°. 3.5m.RF.& spotting 1,700

LU Gun.Stabilimen- reinforced con- scopic sights;range 1,200 type.Turret telescope in CP; —1 to Armstrong crete; concrete to target estimated mount• comm.by voice tube

Puzzuoli. embr. Elev, telephone & voice & telephone. CQ -5° to /145. tube to CP. U-9 3 15.5cm.,60 cal* N On concrete pe- Direct Fire tele- 30,000 Yes 41 thru < F-14 1 75mm.Fid.Gun, A Cave. Direct Fire w/pan- 8,000 Yes 26 Gun.Turret type destals level scopic sights;3.5m. 1,000 46,& 48

T.38 oramic sight. 300 (From Cruiser w/ground. Elev. RF;20 power 12cm. oCL F-15 1 75mm.Mtn.Gun, A Cave. Direct Fire. 8,000 No NAGAMI) -5° to /55°. binoculars for T.94 600 spotting;comm.by

— F-16 1 12cm.,45 cal., N Cave w/concrete Direct Fire;tele- 10,900 Yes voice tube,tele­3rd yr.type embr. Elev. scopic sights; tel- 2,500 phone & buzzer. CD.Gun. -3° to /13°. ephone and voice U-10 2 75mm.Mtn*Gun, A Caves(it was Direct Fir*e sights; 8,000 Yes

tube. (1-T.41;1-T.94) planned to con-lm.RF;communi- 800 F-17 1 75mm.Mtn.Gun, A Cave. Direct Fire. 8,000 No nect the caves). cation between

i

T.94 500 Elev.T.41,-5°to guns by runner. z F-18 1 75mm.Mtn.Gun, A Cave, Direct Fire. 6,000 No /40°;T.94,-10°

T.41 500 to /45°. CO F-19 1 75mm.Mtn.Gun, A Cave. Direct Fire, 6,000 No U-ll 2 14cm.,50 cal., N Caves connected Direct Fire sights; 18,700 Yes 37 & 39 O T.41 600 3rd yr.type Gun. Elev.-3°to/23°. 2.5m.RF;comm.by 1,000 Z F-20 1 8cm.Gun,Arm- A Cave. Direct Fire. 8,800 No voice tube between

strong. 300 guns & to CP. CO F-21 1 75mm.Mtn.Gun, A Open emplace- Direct Fire. 6,000 No

T.41 ment on Tsis I ) 300 LU E-l 4 12cm.DP.Guns, N Concrete revet- T.2 Director w/2m. Yes

10th yr.type. ted AA posi- stereoscopic RF. _J U-l 1 75mm.Mtn.Gun, A Cave. Direct Fire. 6,000 No tions. Elev.0° data transmission % T.41 to/75°.Excel- system installed; o U-2 1 15cm.,40 cal* N Open revetted Direct Fire using 10,900 Yes lent installa- 12cm.scope at B.C.

Gun.Stabilimen- position.Elev. 1 telescope;range 200 tion. station;telephone to,Armstrong -2° to /20°. scale on sight; cal- & voice tube comm. Puzzuoli*Ser. Loading machine ibrated to 10,000m,; 745 made in adjacent to em-CP.directly in rear o 1900.Pointing & placement . of gun;no commun- UD-1 1 12cm.DP.Gun, N Cave in rock Direct Fire sights; 13,200 Yes Training accom- ication.. 10th yr.type. cliff,loose rock no comraunlcation. 2,000 < plished by one parapet;steel man • Init ial muz- plate base not zle velocity set in concrete. 700m. per sec. Elev.-5°to/15°.

U-3 4 Rocket Launch- A In open pit. None;direct laying; 350 Yes 20 UD-2 1 75mm.MtA.Gun, A Cave. Direct Fire. 8,000 No ers for 60kg* no communication. T.94 770

CO rockete.Local- UD-3 1 75mm.Mtn.Gun, A Cave. Direct Fire. 8,000 No LUCO ly manufactur- T.94 660 Z ed on Dublon I* UD-4 1 75mm.Mtn.Gun, A 2 caves connec- Direct Fire. 6,000 No LU U-4 1 15cm.,40 cal* N Open revetted Direct Fire using 10,900 Yes T.41 ted for firing (6,000) LU Gun.Stabilimen- position.Elev. telescope; no 500 the 1 weapon. 500 Q to Armstrong -2° to /20°. communication. (880) LU Puzzuoli»Ser. UD-5 1 75mm.Mtn*Gun, A 2 caves connec- Direct Fire. 6,000 No CO 819. T.41 ted for firing (6,000) LU U-5 1 75mm.Mtn*Gun, A Cave w/concrete Direct Fire only; 2,000 Yes the 1 weapon. 800 Z

T.41 deck connected communication by 300 (600) to CP. Elev. runner. -3° to 0°.

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JAPANESE DEFENSES O N TRUK ATOLL, CAROLINE ISLANDS. CINCPAC-CINCPOA BULLETIN 3-46, 15 M A R C H 1946;

10

ARTILLERY AND ORDNANCE

1•

Army or Navy

Emplacement I Fire Control • Effective

Ranges (Yds)

Max.-Min.

Inspected

Pioture

No, Fition

ber

Number 1 Wearons

Type, Army or Navy

Emplacement i Fire Control i Effective

Ranges (Yds)

Max.-Min.

Inspected

Pioture

No*

Weaoons (Position

Number

iNumber

Type. iICH 1946

Li.

— - P-1 5 12cm.,45 cal,, N Cut type revet- T.2 Director & dir- Ye 8 49 T-14 2 15cm.,40 cal* N Cave* Direct Fire tele- 12,100 No DP.Gun,10th ments lined w/ ect fire sights; Gun8.Stabili- scopic sightBjl-^m. 1,500

in yr. type. palm logs. 2m.RF w/altitude mento Arm- coincidence RF* convertor;data strong Puzzuoli,

1

transmission sys­tem; powered by 2

1-15 1 75mm.Mtn.Gun, T.94

A Cave* Direct Fire* 7,600 330

No

en Z

3kw,generators;tel­ephone & voice

T-16 1 76mm.Mtn*Gun, T.41

A Cave* Direct Fire* 2,300 660

No

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• P-2 1 12cm.,45 cal., N Cave-lined w/ tube comm. Locally manufac­ 10,900 Yes 47

T-17 1 75mm.Mtn.Gun, T.41

A Cave* Direct Fire* 3,300 190

No

_i DP.Gun,10th corrugated sheet tured direct fire 2,200 T-18 1 75mm.Mtn.Gun, A Cave* Direct Fire* 2,500 No

00 < P-3 3

yr. type.

75mm.AA Gun, N

metal. Elev. -4° to /15°. Open revetment.

sights;no comm.

Direct Fire sights; Yes T-19 1

T.41 75mm.Mtn,Gun, T.41

A Cave, Direct Fire* 165

2,200 165

No

O T.88 2m.RF;telephones. T-20 1 75mm.Mtn.Gun, A Cave, Direct Fire, 2,600 No a.

Mm

P-4 2 75mm.Mtn.Gun, T.94

A Open emplace­ment (caves pro­posed); field of

Direct Fire, 8,000 200

No T-21 1

T.41 75mm.Mtn.Gun, T.41

A Cave, Direct Fire* 165

2,100 770

No

% fire to N.by T-22 4 15cm,,40 cal* N Caves w/concrete Direct Fire:tele­ 10,900 Yes

z P-5

P-6

1

1

75mm.Mtn.Gun, T.41 75mm.AA Gun,

A

N

swinging 1 gun around. Cave(on Tarik I.)Open revetment

Direct Fire,

Direct Fire,

6,000 No

No

Gune.Stabili­mento Ana-strong Puzzuoli

Ac rook embrs. Elev*-4°to/17°

scopic eights*3m. • coincidence RF;tel­ephone & buazer.

2,000

*

T.88 to fire AA.

a T-1 1 12cm.DP.Gun, N Cave, Direct Fire, 13,200 No z< ir#

T-2 1 10th yr.type. 75mm,Mtn*Gun, T.94

A Cave, Direct Fire* 1,000 2,180 330

No

LU T-3 1 75mm.Mtn.Gun, A Cave, Direct Fire. 2,180 Z T.94 435 _ i

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T-4 3 15cm.,40 cal, P n r i ­ Q •*- j-t V> O ­1WrUnS, uuaDj.ll­mento,ArmstrongPuzzuoli,elec­tric firing cir^ on i

N Connecting caves w/concrete & rock embrs'tun­nel to CP.Eiev, -4° to /L7°*

Direct Fire;tele­scopic sights; 3m, coincidence RF; telephone,voice tube & buzzer.

14,300 2,500

Yes ••m

-i ^% T-5 1 75mm.Mtn.Gun, A Cave connecting Direct Fire. 2,180 No U T.41 w/alternate po­ 330

sition. Alternate Pos ­

T-6 1 75mm.Mtn.Gun, T.41

A Cave. Direct Fire. 550

2,180200

No

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T-7

T-8

1

1

75mm.Mtn.Gun, T.41 75mm.Mtn.Gun, T.94

A

A

Cave,

Cave,

Direct Fire*

Direct Fire*

3,000 440

1,600 330

No

No

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T-9 1 75mm.Mtn.Gun, T.94

A Cave connecting w/alternate po-

Direct Fire* 7,600 870

No W UJ sition. O T-10 1 75mm.Mtn.Gun, A Cave connecting Direct Fire* 7,600 No UJ T.94 w/alternate po­ 1,950 CO sition. UJ T-11 1 75mm.Mtn.Gun, A Cave, Direct Fire, 7,600 No

< T-12

T-13

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T.94 7c5nm V*~n Gun

T.41* 75mm,Mtn,Gun,

A

A

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Cave,

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Direct Fire.

1,100 DjUUU

4407,600

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No Picture Mo. do (PM333) PARTIAL VIEW OF FIELD OF

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T.94 330 2ocu GUM r. MOEM: Position M-ai.

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CO CO JAPANESE DEFENSES ON TRUK ATOLL, CAROLINE ISLANDS. CINCPAC-CINCPOA BULLETIN 3-46, 15 MARCH 1946

ARTILLERY AND ORDNANCE

MAINTENANCE AND REPAIR FACILITIES.

In general, maintenance and repair facilities according to our standards did not exist in the Japanese Army at *his installation. Apparently no maintenance organization existed as such. The using units performed their own first and X limited second echelon maintenance. Early in the war, third echelon assemblies were shipped to JAPAN and new or rebuilt assemblies were shipped to TRUK. Later in the war, the m y depended on the Navy for such higher echelon maintenance as was required and which could be performed by the Navy shops.

Up to 30 April 1944, when its shops were bombed out, the Navy had very adequately manned and equipped repair facilities which were capable of malting very extensive repairs on a wide varlbwy of materiel.

In addition, prior to January, 1944, three Japanese repair ships - a part of z the Grand Fleet - assisted island personnel in the maintenance of materiel.

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A map showing the extent of the Navy maintenance facilities before and after _i the bombing of 30 April 1944, ana subsequent shops constructed, is included as a CQ part of the Engineer's Annex to this report.

Following the bombing of 30 April 1944, shop equipment which was still service-o able, or could be made so, was in most cases moved underground. The principal underground machine shop is indicated on the above-mentioned annex. The floor is z rock-dirt and very wet, requiring a pump to control the water level in the shop. Due to the extremely damp conditions, all machine and hand tools are In a very poor state of preservation.

The blacksmith shop consisted of a small open shed.

Z The foundry was reduced to one medium-sized oil-fired cupula (see picture No.

67) from which small xron castings could be produced. It was found at approximately its original position.

CO

Q The welding shop, while in its original position, was damaged. Due to the

Z lack of proper welding rod, soft iron wire cut to proper length and dipped In an asbestos paste was used. The gasoline-driven direct-current machines were still

CO in operation. Acetylene welding was stopped with the destruction of the oxygen and acetylene plants.

Partial destruction of the carpenter shop reduced the production of pattern-making and carpentry to a hand operati-on. o

The above shops each had well-equipped tool rooms with an adequate supply of micrometers (both inside and outside), verniers, scales, calipers, electric drills, taps and dies, planes, chisels, carpentry and blacksmith tools.

Following is a list of the principal machine tools with which the above shops are now equipped and which were in operating condition:

Picture No. 1 - Shaper (Asano-Jyuko) 16" stroke, 16" horizontal and 14W ver- 57

tical travel table. Individual motor drive. z 1 - Lathe, 16" swing X 48" between centers, Monarch Machine Tool o Co. Navy Yard Number 9-104, Back geared, individual motor CO drive. UJ CO 1 - Lathe, 16l! swing X 60fl between centers, quick change gears,

individual drive, taper attachment, South Bend. Z 1 - Lathe, 8I! swing X 24" between centers, Japanese manufacture,

WSK-3, back geared, taper attachment, turret type tool holder, Individual motor drive.

3 - Lathe, 8H swing X 26" between centers, precision type, com- 58 CO plete with collet set, Japanese manufacture, individual motor LU drive. Z 2 - Drill press, 22" swing, floor type, movable table, Individual 59

motor drive, power feed, Minoura & Co., Ltd. 1 - Universal Milling Machine, The Kempsmlth Mfg. Co., Milwaukee,

Wisconsin., Navy Yard No. 9-78, year purchased 1921, cost Si.793. individual motor drive.

Picture No.

1 - Universal grinder, 8" swing X 24" between centers, Br^wn & Sharpe No. lu.

1 - Radial Drill, 48w radius X 48" vertical olearance, Minoura & 66 Co., Ltd., individual motor drive.

1 - Shaper, vertical (or Keyway cutter) 26M dla table, 14" 61 stroke, Kubooho, Tokyo, Individual motor drive.

1 - Pipe threader, i-3/8" diameter capacity, equipped with bolt thread fly cutters only, Landis Machinery Co., Waynesboro, Pa., belt drive.

1 - Lathe, 14" swing X 48" between centers, heavy duty, turret 60 type tool holder. J.F.K. Mfg., Osaka, individual motor drive.

2 - Lathe, 16" swing X 28" between centers, gap bed, Japanese 62 manufacture, belt drive.

1 - Lathe, 16" swing X 48" between centers, with taper attaoh­ment, Amerioan Tool Works Co., Cincinnati, Ohio. Navy Yard No. 9-77, Purchased 1931, Cost $3,161.

1 - Boring Machine, horizontal, 51" spindle head to support bear- 63 ing, the Fairbanks Co., Navy Yard No. 9-5, purchased 1909, cost $1,125.

1 - Turret lathe, 22" swing X 72" between centers, gap bed, the 64 Rahn Larmon Co., Cincinnati, Ohio, Navy Yard No. 340B-8, purchased 1921. Property of the U. S. Army, P4299.448C, No. 124 Ordnance Department, belt drive,

1 - Planer, open side, bed 28" X 120", Petrick and Harvey Machine 65 Co., belt drive.

1 - Drill press, sensitive type, 12" swing, floor type. 2 - Lathe, 6fl swing X 12" between centers, bench type, precision,

with turret attachment, not installed to operate motor drive. 1 - Punch and shear, Yamokawa Press Mfg. Co., Individual motor 66

drive. 1 - Sheer, gate, 51 capacity 3/8" stock. 68 1 - Hammer, individual motor drive. 69 1 - Furnace, heat treating, 18" wide X 24" deep X 12" high. 1 - Forge, anvil, blacksmith vioe, hand tools.

The 104th Alrforce Arsenal (Navy), prior to 17 February, 1944, was laid out as indicated in the plan included as a part of the Engineer's annex to this report. At the time indicated, it was destroyed by bombing. At present, the power-plant building is standing. Machines in the shops were destroyed and have been removed. The only indication of the machine tools is the "Wooden Shop" (Carpenter Shop). The following machinery is in that location but is unserviceable:

2 - bandsaw 36" 1 - Joiner 1 - 1 4 " planer 1 - 1 8 " planer 1 - 16" swing X 36" between centers, lathe 1 - Circular saw and Joiner

The 4th Construction Department Repair Shop (Civil Engineering Department of the Japanese Navy) has a machine and repair shop which was evidently used for the repair of its equipment and for such manufacture as was required. The machine tools and other equipment were in good condition but of very old manufacture (possibly before 1900)• The machine shop was powered by a single cylinder horizontal YANMAN Diesel Engine, all machines being driven from overhead pulleys and line shafts. Shop equipment included the following:

1 - Lathe, 18" X 96", gap bed, turret type tool holder, back geared. 1 - Lathe, 18" X 30", gap bed, turret type tool holder, back geared. 1 - Lathe, 16" X 30", gap bed, turret type tool holder, back geared. 1 - Drill press, 22" swing -Tloor type, hand feed. 1 - Milling machine, table 7W X 29", with dividing head. 1 - Shaper, 18" stroke, with vice. 1 - Grinder, pedestal type, 10" wheels.

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Picture No. 50 (PM 25) i.oookv GENERATOR ­ l.yoohp DIESEL Picture No. 51 (PM 26) 74kw GENERATOR ­ g-ohp DIESEL Picture No. 52 (PM 39) 6$kva(ac) - 65ku>(dc) GENERATOR ENGINE ENGINE. lQohp diestl engine.

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P i c t u r . * ^ o . 5 3 (PM40) iookva(ac) GENERATOR: 150HP Picture No. 5 4 W 35) UNDERGROUND MACHINE SHOP: View Picture No. 55 (PM 36) UNDERGROUND MACHINE SHOP: View die set engine (unserviceable). from e nt ranc e. from inside the shop.

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Picture No. 5 6 (PM 30) RADIAL DRILL: 48" radius X 48" Picture No. 5 7 (PM 27) SHAPER: (Ansano Jyuko 16" Picture No. 58 (PM 28) LATHE: 8" sum? X 26" vert ical c Learance, indiv idua I motor drive, Mtnoura and stroke, table travel 16" horizontal X 14" vertical, centers, precision type, comtlete- with col Co., ltd. indiv idua I motor drive. individual motor drive. $ E ^A ftTi

35

ARTILLERY AND ORDNANCE

A email blacksmith shop, with two forges and two anvils, located adjacent to TOTAL QUANTITIES OF FIRE CONTROL ITEMS. the machine shop is presently used to store kafir corn. One of the lathes listed above was equipped with attachments for threshing, and there was a grist mill for The following inventory was compiled by the Japanese and is believed to be grinding this corn. quite complete and accurate. The inventories do not include such items as binoculars

end compasses which were used by the Japanese Naval Air Unit on TRUK. A two-stall garage-type shop was used to repair Construction Department

vehicles, air compressors, bicycles, etc.

A saw-mill was operated to make rough lumber for construction purposes. A 41 diameter band-saw mounted with a cradle for passing and handling the logs, was

2 m

driven by a diesel engine. Navy Fire Control Items:

The above installations were equipped with limited hand tools, such as: Quantity Item Picture Number micrometers, calipers, verniers, scales, blacksmith and mechanic's hand tools.

2 Type 94, 4.5m Range Finder. 24 The 41st Garrison Machine Shop and Warehouse had evidently been a small 1 Type 93, 4.5m Range Finder.

combination shop for general repairs and maintenance. It had some permanent equip­ 1 BU Type, 4.5m DP Range Finder. ment installed as follows: 1 BU Type, 3.5m Range Finder.

1 BU Type, 2.5m Range Finder. CQ 1 - Lathe, 18" X 36", quick change gears, heavy duty, Jap manufacture 2 Waterproof, 3.5m light Range Finder.

similar to a modern South Bend Lathe, taper attachment, of very modern 5 Range Finders. type, individual motor drive. Picture No. 71. 2 Range change.

1 - Grinder, pedestal type, 12" wheels. 2 Type 13 Range Clocks. o a. 1 - Drill press, 22" swing, floor type, hand and power feed. 1 15cm binoculars. Z 1 - Saw, band, 36" diameter wheels (woodworking) Individual motor drive. 57 12cm binoculars.

1 - Circular saw, 12" diameter blade, tilt top, table type, with complete set 22 12cm high angle binoculars. dado heads (woodworking) individual motor drive. 3 12cm observation glasses.

1 - Planer, 16" blades (woodworking) individual motor drive. 2 12cm binoculars, Type 97 waterproof. 1 - Sharpener for woodworking band saws. 42 8cm binoculars. 1 - Lathe, 16" X 40" (woodworking) individual motor drive. 31 8cm high angle binoculars. 1 - Bla.cksmithing outfit complete with forge, anvil, shear, vices and hand 10 6cm high angle binoculars.

tools. 8 Model 3 observation glasses. 1 - Furnace (in ground) oil-fired for producing iron castings. 1 66cm range finder.

z

to Q 1 3cm binoculars, high angle. In addition, the shop was equipped for both acetylene and arc welding. A 22 Z Prismatic binoculars, Model I. complete supply of hand tools for use with the above machine tools was on hand. 1 10 power prismatic binoculars.

461 7 power prismatic binoculars. to Evidently a number of machine tools was received from JAPAN which it was 19 6 power prismatic binoculars. 33 Wall clock, weekly wind, luminous. 48 Wall clock, dally wind, luminous.

LU thought best not to install for operation. These were stored in caves and recently had been moved to this shop for storage. These machines of very recent manufacture Z and very modern design are listed as follows: i 11 Wall clock, weekly wind. _

38 Wall clock, daily wind. 1 - Lathe, 18" X 48" between centers, heavy duty type, quick change gears, 45 Wall clock. (similar to Reed-Prentice), individual motor driven. 25 Stop watch, model 1-B.

o < 1 - Lathe, 18" X 30" between centers, heavy duty type, quick change gears, 3 Stop watch, model 3.

170 Stop watch. 7 Ordinary binoculars.

(similar to Reed-Prentice), Individual motor drive. 1 - Shaper, 20" stroke, with vice, (similar to Cincinnati) Individual motor

drive. Picture No. 72. 1 - Circular saw 12" blade, tilt top table type complete with dado heads, Army Fire Control Items:

individual motor drive. 1 - Drill press 22" swing, power and hand feed floor type, individual motor 1 Type 96 Searchlight Instrument.

drive. 595 3 - Welders, electric, AC transformer type. 43

13th yr type Binoculars. Type 89 Binoculars. z

o en Ul

603 Type 93 Binoculars. It is felt that prior to the bombing of 30 April 1944, the maintenance and 13 Type 37 Artillery glasses.

repair facilities of TRUK were such that very extensive repairs, including fifth 38 Type 93 Artillery glasses. echelon, were possible and had been accomplished. Probably the most serious 83 Type 93 50cm observation glasses. to handicap was the difficulty encountered with procurement of supplies from supply Z

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30 Type 93 Field range finder. bases In JAPAN due to the distance to be traveled. This lack of supply became more 2 8th yr type Heavy range finder. serious as our attacks reduced the tonnage of Japanese shipjjing of manufactured and 1 Type 89 AA binoculars. 17 7 power periscope binoculars.

raw materials which was getting through to TRUK. After the bombing of 30 April 1944, the maintenance facilities were curtailed to a large extent, until they were re­ 1 8cm binoculars.

1 12cm binoculars. LU to located and re-established as indicated in the above paragraphs. However, they were LU never able to approach the capabilities which were formerly enjoyed. It is felt Z that their facilities are roughly 10 to 20 per cent of what they previously had

been. By observation and conversation with Japanese officers, it is concluded that maintenance was practically at a standstill due to the lack of fundamental supplies. Little or no stock of major items, assemblies, sub-assemblies or raw materials existed at the cessation of the war.

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1 12cm high angle binocular range finder. 15 Type 98 Light ground fire control instrument.

36

I

P i c t u r e N o . 5 9 (PM 2 9 ) D R I L L P R E S S : 2 2 " s w m ? , f l o o r P i c t u r e N o . 6 0 (PM 3 2 J L A T H E : 1 4 " s u m ? X 4 8 " b e t w e e n t y p e , n t o i / a H e t a b l e , i n d i v i d u a l m o t o r d r i v e , p o w e r f e e d c e n t e r s , h e a v y d u t y t u r r e t t y p e t o o l h o l d e r , m d i v i d u a I M m o t i r a a n d C o . , l t d . m o t o r d r i v e , J . F . K . M f g . . O S A K A .

P i c t u r e N o . 6 2 (PM 3 3 ) L A T H E : * 6 " s w i n g X 2 8 " b e t w e e n P i c t u r e N o . 6 3 (PM 3 4 ) B O R I N G M A C H I N E : h o r i z o n t a l , 5 1 " c e n t e r s , g a p b e d , J a p a n e s e m a n u f a c t u r e , b e l ' t d r i v e . s p i n d l e h e a d t o s u p p o r t b e a n n f . T h e F a i r b a n k s C o . , N a v y

Y a r d N o . 9 - 5 , p u r e h a s e d i g o g . C o s t $ 1 , 1 2 5 .

P i c t u r e N o . 6 1 (PM 3 1 )c u t t e r . ) 2 6 " d t a . t a b l ed r i v e , K u b o c h o , T o k y o .

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P i c t u r e N o . 6 4 (PM 3 J ) T U R R E T L A T H E : 2 2 " s w t n f X 7 2 " b e t w e e n c e n t e r s , g a p b e d . T h e R a h n L a r m o n C o . , C i n c i n n a t i , O h i o , N a v y Y a r d N o . 3 4 0 B - 8 . p u r c h a s e d 1 9 2 1 , P r o p e r t y o f U . S . A r m y P 4 2 9 9 . 4 4 8 C , N o . 1 2 4 O r d n a n c e D e p a r t m e n t .

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P i c t u r e N o . 6 5 (PM 3 8 ) P L A N E R : O p e n s i d e , b e d 2 8 " X P i c t u r e , 1 , 0 . 6 6 (PM 4 2 ) P U S C h AND S H E A R : I n l i v i l u a l m o t o r Picture No. 6 7 (PM 41) COPULA: O i l S c i v y r e p a i r s h o p 1 2 0 " , b e l t d r i v e , P e t n c k a n d H a r v e y M a c h i n e C o . d r i v e , Y a n o j a w a P r e s s M f g . C o . , o l d f i a v y r e p a i r area.

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37

I

ARTILLERY AND ORDNANCE

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Quantity Item

3 Gunner's slide rule. 2 Calculating boards. 1 Type 98 Fire calculating board. 1 Type Mark I Plotting board. 1 Type Mark II Plotting board. 5 Goniometer. 4 Protractor. 1 Trajectory and wind plotting board. 8 Stop watch.

13 Portable thermometer. 2 Type 93 Height finder.

752 Type 98 Night compass. 3 Type 1 Plane altitude measuring instrument. 3 Type 2 Plane altitude measuring instrument. 9 Type 97 Rifle type stereoscopic sight.

15 Type 97 Stereoscopic sight. 5 Type 98 Target range finder.

15 Gun sight direction block. 1 Clinometer. 2 Clinometer spectacles. 4 Mil slide rule.

TOTAL QUANTITIES OF VEHICLES (NO TACTICAL VEHICLES WERE FOUND ON TRUKK

The following inventory was compiled by the Japanese. Two Inventories were submitted, one showing total quantities at TRUK, the other showing quantities on each island. Discrepancies exist in comparing the two. The following is believed therefore to be only fairly complete and accurate.

Navy Vehicles;

Quantity Vehicle

196 Trucks. 34 Personnel carriers. 15 Fire trucks. 13 Motorcycles with side cars

(believed to be motor tricycles). 1 Sidecar (with motorcycle). 7 Machine gun carts.

11 Tractors. 1 Three-wheeled fire cart. 5 Trucks equipped with crane.

11 Fuel oil trucks. 2 Ambulances. 2 Air charging truck (torpedoes). 5 Ditchers. 1 Sprinkler truck. 2 Trucks for transporting torpedoes. 1 Oxygen generating truck. 1 Searchlight truck. 4 Water supply trucks.

Army Vehicles;

Quantity Vehicle

75 Trucks. 3 Type 96 Trailer car. 1 Ambulance. 7 Passenger car. 3 Type 95 wheel drive passenger car, 1 Light repair truck. 94 Type 39 Trucks.

TOTAL QUANTITIES OF WEAPONS AND AMMUNITION.

The following Inventory was complied by the Japanese and is believed to be quite complete and accurate insofar as weapons are concerned. The ammunition inventory is of unknown accuracy since all ammunition had been dumped at sea prior to the arrival of the Study Group. These inventories do not include bombs and bomb fuzes, aircraft machine guns nor the ammunition for these guns which were used by the Jap Air Unit on TRUK, nor the ammunition stored at TRUK for the Imperial Fleet.

Navy Ordnance Equipment: AMMUNITION

QUANTITY TYPE CALIBER WEAPON (ROUNDS) PICTURE NO.

4 Safety 45 20cm Gun 946 3 3rd yr. 60 15,5cm Gun 773 13 Safety 40 15cm Gun 3,103 4 Safety 45 15cm Gun 3,706 4 41 40 15cm Gun 0 14cm Gun 3,855 7 3rd yr. 50 12cm Gun 2,780 3 41 40 12cm Gun 262 2 89 40 12.7cm Multiple Mount 2,908 CD

DP Gun 7,337 AA 29 10th yr. 45 12cm AA Gun 1,957 AA

609 CD 3 3rd yr. 40 8cm AA Gun 2,122 AA 1 5th yr. Short 8cm AA Gun 132 9 7cm AA Gun 3,237 23 3 8cm Mortars 3,957 2 1 47mm Mobile Gun 272 2 94 37mm Anti-Tank Gun 1,984 1 2 30mm MG, fixed 1,700 1 2 20mm MG 91 99 MK 1 20mm MG 47,207 73 96 25mm Multiple Mount MG 23 96 25mm Single Mount MG 472,835 3 93 13mm Multiple Mount MG 89 93 13ram Single Mount MG 265,064 1 Hotchkiss 13mm Quad. Mount MG

140 92 7.7mm Single Mount MG 28 92 7.7mm Flex, Mount MG 1,137,094 1 Lewis 7.7mm MG 8 Model 1 7.7mm Flex. MG 31 92 Heavy MG 272,928 177 99 Light MG 1 3rd yr. MG 51,100 15 96 Light MG 3 11 Light MG

6,567 99 Rifle 1,369,197 1,214 38 Rifle 1,120,401

27 I Rifle 9 W

325 14 Pistol 189,443 45 Army Pistol # 56 BE Automatic Pistol 85 25 Very Pistol 10 100 Flame Throwers 7 Large Model Flame Throwers 78 26 Locally Manuf. Bomb Rocket Launchers 20, 82 11 57 Bomb Rocket Launchers

for land use. 100 89 Heavy Grenade Dischargers 7,064 211 100 Grenade Launcher 2 95 AA MG for land use. 1 2 AA MG for land use.

38

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w JAPANESE DEFENSES ON TRUK ATOLL, CAROLINE ISLANDS. CINCPAC-CINCPOA BULLETIN 3-46, 15 MARCH 1946

1

ARTILLERY AND ORDNANCE

The Navy had the following a d d i t i o n a l explos ives on hand: Army Ordnance Equipment; (Continued)

X EXPLOSIVE OR ROUNDS TYPE QUANTITY TYPE CALIBER WEAPON AMMUNITION (ROUNDS) PICTURE NO,

z t— Ul

CQ

<

o a.

en

20 6,000

6 1,042

40 61

109 61

660 48

243 210 152

25 20

921,769 48,033 11,133

6,133 11,000 14,500

1,500 kg. 208 954 644 m. 590 m.

84

15cm How. (4th yr) Type 97 Automatic Gun, HE shells Type 92 Infantry Gun Sound Shells Experimental Sound Sphere Type 90 Booster Charges Type 91 Smoke Shells Type 89 Smoke Shells Mod. 1 Signal Shells Torpedo Firing Charges Signal Lights (flares) Slow Fuzes Smoke Shells Signal Rockets Launching Charges All types of Fuzes All types of Primers Types 91 and 96 Booster Charge Cylinders All types of Booster Charges Ordinary Primers Electric Primers Type 88 Explosive Charge MK 2 Demolition Hooks Land Demolition Charges Land Fuze Safety Fuze Type #6 Land Explosive Charges

12 3rd yr. 81mm Mortar

15 23

42 81 37 41 34 9 18

3

3 2 6 7 8 46 27

97 97

92 94 1 94 41 98 99

98

38 95 91 Armstrong 88 93 100

90mm 20mm

70mm 37mm 47mm 75mm 75mm 37mm 81mm

20mm

75mra 75miu 105mm 8 cm 75mm

Mortar Automatic Gun

Infantry Gun Anti-Tank Gun Anti-Tank Gun Mountain Gun Mountain Gun Anti-Tank Gun Small Mortar

Automatic Cannon

Improved Field Gun Field Gun I'^witzer 8cm 40 cal. Gun AA Gun Flame Thrower Flame Thrower

4,680 (also for type 99) 5,557

57,646 (also for auto cannon)

21,003 40,568 17,590 77,516 10,727 6,334 4,680 (also for type 3) 57,646 (also for auto gun)

3,031 3,067 3,341 2,306

5,474

The Army had the following additional explosives on hand:

Cartridges

QUANTITY TYPE DESCRIPTION

a z CO

ui

z

o as

=3 as

z o CO UI CO

Z

LJJ

a U l CO UJ

Army Ordnance Equipment:

QUANTITY TYPE CALIBER

421 66

11,699

100 811 243 159

21 1,110 1,192 475 4 3 50 739 376 388

5 8 19 18 5

58

38th yr. 38th yr. 99

26th yr. 14th yr. 94 Various

10th yr. 89 100 2

11th yr. 96 99 92 92 92 92 92 97 93 97

6.5mm 6.5mm 7.7mm

8mm 8mm 8mm 6.35 to 7.65mm 50mm 50mm

7cm 6.5mm 6.5mm 7.7mm 7.7mm 7.7mm 7.7ram 7.7mm 7.7mm 13mm 13mm 81mm

WEAPON

Infantry Rifle Cavalry Rifle Short Rifle

Pistol Pistol Pistol Pistol

Grenade Discharger Grenade Discharger Rifle Grenade Launcher Grenade Discharger Barrage Mortar Light MG Light MG Light MG Heavy MG Heavy MG AA Machine Gun Fixed Machine Gun Flexible MG Mobile Heavy MG Single Mount MG Mortar

AMMUNITION (ROUNDS) PICTURE NO

660,125 3,887,222 (also for L.MG)

4,819

41,718 3,038

Listed In next paragraph

26 3,887,222 (also for rifles) 134,244

4,485,489

10,069 31,583

1,272 63,900 63,763 7,045 2,585 2,945 2,677 211

1,392 2,155 2,458

43 2,147

15 7,120 5,657 382 767 401 411 Kg 240 807

6,000 Kg 247 Kg 140

2,220 Meters 4,292 1,778 2,449

91 97 99 94 94 94 99 94

60 Kilo 97 97 93

99

1 Kg

Mark 1

10th yr 100

Hand Grenade Hand Grenade TIand Grenade Small Smoke Candle Large Smoke Candle Floating Smoke Candle Self-projecting Smoke Candle Training Smoke Candle Experimental Smoke Grenade Incendiary Grenade Frangible Incendiary Grenade For Bomb-throwing Mortar Yellow Explosive Block Yellow Explosive Stick Anti-Tank Mine Anti-Personnel Mine Bangalore Torpedo Yardstick Mine Demolition Can Fine grained Powder Explosive Can Improved Land Mine Dynamite Karitto Powder Incendiary Powder Primacord Signal Shell Flare Hand-launched Molotov Cocktail

For hand throwing and grenade dischargers and launchers.

z

40

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JAPANESE DEFENSES ON TRUK ATOLL, CAROLINE ISLANDS. CINCPAC-CINCPOA BULLETIN 3-46, 15 MARCH 1946.'

X

o*

L

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FIGURE NO. 4 AND SEARCHLIGHT10WING FIELDS OF FIRE

POSITIONS

y^ CxZZ.

SEARCHLIGHT ARMY ARTILLERY NAVY ARTILLERY

AND FIELD OF FIRE AND FIELD OF FIRE

4 2

URE NO. 7 ISLAND

I

a:

z I— LU

CQ

o Q.

z

z

z

CO

UJ

Z _i

o

FIGURE NO. 6 UDOT and EOT ISLANDS

z o CO UJ CO

Z

UJ CO UJ

Z

a.

ALL SCALES = r.25,000

ARTILLERY AND SEARCHLIGHT POSITIONS SHOWING FIELDS OF FIRE

SEARCHLIGHT ARMY ARTILLERY AND FIELD OF FIRE NAVY ARTILLERY AND FIELD OF FIRE mm iOBSTRUCTION IN FIELD OF FIRE

43

I GARRISON

CO

o CL U

Z v 0

Z

CO

Z < to

DUBLON ISLAND

DUBLOW TOW

o a:

7 W T

Z

o CO UJ CO

EAPLANE BASE ETEN^iSLAND

at CO

FIGURE N 0 . 8 -ARTILLERY AND SEARCHLIGHT POSITIONS

SHOWING FIELDS OF FIRE

wm& -1:25,000

o Ccc:

SEARCHLIGHT ARMY ARTILLERY AND FIELD OF FIRE NAVY ARTILLERY AND FIELD OF FIRE

OBSTRUCTION IN FIELD OF FIRE 44

JAPANESE DEFENSES ON TRUK ATOLL, CAROLINE ISLANDS. CINCPAC-CINCPOA BULLETIN 3-46, 15 MARCH 1946

MILITARY ENGINEERING

ENGINEER AND CONSTRUCTION TROOPS.

o The staff engineer of the Japanese 52nd Division was Major Satoichl TANABE, whose duties were to advise, coordinate and supervise fortification work performed by infantry units vithln the division. No Army engineer troops existed at TRUK as far as numerical designations were concerned. However there was evidence that some individuals and units had received engineer training before.departure from JAPAN. One officer interrogated on UMAN stated that he was the engineer officer for tnat island and that he had a "pioneer" platoon of forty men. This officer stated further that his men had been a part of an engineer regiment in JAPAN and that one battalion departed for TRUK with engineer equipment. However the ship bringing the equipment was reported to have been sunk en route. Upon arrival this battalion's personnel were distributed among the Infantry units and lost their ef­fectiveness as engineers for any sizeable construction project. The one platoon z which appeared to remain together on UMAN was assigned the primary- mission of con­structing offshore obstacles, using local materials and hand labor, and some work In preparing gun emplacements. In the event of a US attack, this platoon was to become a suicide unit to stop US tanks with improvised charges and magnetic type anti-tank mines. The engineer officer stated his equipment was meager and con­

< sisted of picks, shovels, a few explosives, and simple carpentry hand tools. In written replies to questions on engineer organization, the Japanese stated they

o had also a warrant officer and a civilian technician to help supervise the build-of huts and shacks. a.

Z Table A-l shows the Naval Construction Staff and Troop Organization.

TABLE A-l

NAVAL CONSTRUCTION ORGANIZATION - STAFF AND TROOPS Z

CONSTRUCTION COMMAND

CO [NAVAL MINISTER! O •

Z CHIEF CONSTRUCTION COMMANDER IN CHIEF] HEADQUARTERS,JAPAN 4TH FLEET

CO

LJJ [CHIEF 4TH CONST RUCTION DEPT ICHIEF 227TH CONSTRUCTION CORPS! Z

[CHIEFS OF BRANCHES! o

4TH CONSTRUCTION DEPT. ORGANIZATION a: <

TABLE A-l (Cont.)

227TH CONSTRUCTION CORPS ORGANIZATION

RANK

Officer

Senior Civilian

Junior Civilian Petty Officer Seaman

Workers

Total (Branch)

+3 O CD

4-3 • H

si0 u

u bD

H •H

O

H O •H C!

^ uO bD CD G

aw

oS O

•H

(D UD H CS MM

H PS1

CO

£_)CD

4 0 0$

0

<M

CO

CD rH O

H cj O

•H '(JCD

a

<S rH

4-3 O

EH

2 3 2 7

Q

1 2 1 4

7 6 12

160 559 109 4 4 11 11 2 8 6 0

163 564 109 4 4 11 19 10 884

Engineer supply for both Army and Navy was lumped with other supplies under one supply service for each.

In general, craftsmanship was excellent. However, the very limited amount of construction machinery handicapped any large construction program. To construct the airfields, thousands of laborers moved large quantities of earth by hand. An unbalanced sense of the relative strategic or tactical importance of things led the the Japanese to place emphasis on novel installations and to neglect commonplace essentials. Army officers stated that, under an agreement witn higher headquarters, the 4th Naval Construction Unit performed Army work upon request. There was some evidence of a lack of cooperation between the Navy'and Army with respect to this agreement. For example: A Japanese Army officer reported than an Army request for tools with which to.expedite completion of the Army underground divisional CP was denied because the tools were needed on the Navy1s nearby underground CP. It ap­pears that there \reve other naval needs for the tools after the Navy CP was finish­ed. The Army CP is still far from completed.

ORGANIZATION OF THE GROUND.

ply

After the loss of the MARIANAS and the consequent cutting-off of incoming H Hctf supplies, the Japanese plans for the defense of TRUK called for a long term, pro­

tracted resistance* The defense aimed at: minimizing damage from our air attacks -p bDo §' rS o o CD W •H •H 0 Hco P CD - by use of the terrain and protective shelters; annihilating our Invading force at H a.: •H

si 4-3 • 5s O

the beaches; and maintaining the defense as long as possible. Defensive positions were selected to take advantage of the terrain against all forms of attack and to

CD •Ho uCD {50 <DO bD TlJ +3 o •H H CD OH a a uO S W OuRANK EH annihilate the assaulting force at the beach. z o CO Ul CO Z

Officer

Senior Civilian

8

4

11

6

1

0

0

1

0

1

0

0

11

2

4

6

35

2 1

CO UJ

Junior Civilian Petty Officer Seaman

5

1 1

11

29

2

5

2

3

2

0

0

0

1 0 5

14

1

1 6

1 2 8

7 8

Z Workers 1028 4981 7 1 8 107 13 6 6 8 8 5 5 22 8392

Total (Branch) 1056 5038 7 2 6 113 16 668 9 8 7 49 8654

How well these plans would have succeeded is, of course, a matter of conjec­ture, but, in view of the types of emplacements constructed, it is considered likely that naval and air bombardment would have taken a heavy toll of the defen­sive positions on and near the beaches. Troop dispositions, as indicated on the maps in PART TWO, provided generally for a defense in depth based upon the four main islands, MOEN, DUBLON, UMAN, and FEFAN, and token resistance or delaying action on the remaining islands. Considerable emphasis was placed on the ability of the beach defenders to withdraw should our initial assaults succeed. Final re­sistance lines or areas were to be near the summits of mountains on each island. However at the end of the war these last-ditch strong points were Incomplete. For example: only a portion of the division battle CP at the summit of MT. TOLOMEN, DUBLON, had been excavated and the post in actual use was at RARA, roughly in the center of DUBLON and only a few feet above sea level. The Navy battle CP near the peak of MT. TOLOMEN, DUBLON, was completed in July, 1945.

46

P i c t u r e Mo. 86 (PMD C B L O M : Mote viewof fire along shoreof P i l l b o x removed

° i c t u r o . M o . 8 9AT MOEN AIRFIELDt o w a t e r ' s e d g e .m o v e d .

1 0 4 ) 9 7 m m GUN P I L L B O X , M O R T B E A S T B E A C H , t h r o u g h e m b r a s u r e s s h o w i n g g r a z i n g f i e l d l i n e . Dirt and earth c o v e r c a v e s on roof

at time P i c t u r e was t a k e n .

(PM 2 6 6 ) HEAVY MACHINE GUN PILLBOX ON BEACH MO. 1 : N o t e d o u b l e e m b r a s u r e a n d p r . o x i m i t y

E a r t h c o v e r a n d c a m o u f l a g e h a v e b e e n r e -

P i c t u r e Mo. 87 (PM 1 0 5 ) HEAVY MACHIME GUM P I L L B O X , EAST BEACH, D U B L O N : Walls of this p i l l b o x were 5 ' t h i c k . Note f i g u r e . Major S. TAMABE, Staff E n g i n e * - , J a p a n e s e *>2nd D i v . , for c o m ­p a r i n g s i z e . R o c k c o v e r has been r e m o v e d from r o o f .

P i c t u r e N o . g o (PM 1 5 2 ) 37mm AT GUN P I L L B O X , SOUTH BEACH,UMAN: I n t e r i o r , v i e w . N o t e d o u b l e e m b r a s u r e a n d l i m i t e d h e a d r o o m . W a t e r a n d mud o n f l o o r s h o w p o o r d r a i n a g e . N o t e a l s o - o o f s u p p o r t . G r a s s b l o c k e d f i e l d of g r a z i n g f i r e .

P i c t u r t Mo. 88 (PM 1 0 6 ) 9 7 m m GUMC l o s e u p of e m b r a s u r e . Mote e a r t hn a t u r a l c a m o u f l a g e .

P i c t u r e N o . 9 1 (PM 1 2 6 ) EMBRASUREC R 0 S S . R 0 A D , DUBLON: The b a f f l e dr e d u c e t h e n u m b e r of s m a l l a r m semp l a c erne n t .

z t— UJ

P I L L B O X . EAST B E A C H , DUBLOM, and rock c o v e r on roof and

o a.

Q-

z

CO Q Z

CO

o

47mm GUN P I L L B O X , 4TH FLEET o r s t e p p e d e m b r a s u r e w a s t o

r i c o c h e t s e l a n e m e i n t o t h e

Z

o CO UJ CO

z

CO UJ

z

P i c t u r e No. 9 2 (PM 4 0 5 ) 12cm GUN, M T . M I S H I K I , F E F A N : Typical Picture No. 9 9 (PM 4 4 3 ) 12cm AA GUN IN CAVE, PARAM: O r i g i n a l l y Picture. No. 9 4 (PM n o ) 14cm NAVAL GUM CAVE E M P L A C E M E N T ; UMAN naval a r t i l l e r y cave e m p l a c e m e n t . E n t r a n c e to p o s i t i o n is by gun was part of 6 - g u n b a t t e r y with AA m i s s i o n , later e m p l a c e d One of a p a i r of CD gun c ove ring SOUTH Pass. Gun o r i g i n a l l y t u n n e l to r e a r . R o c k wall at f r o n t a f f o r d s some p r o t e c t ion to fire on s u r f a c e c r a f t n o r t h of PARAM. Note use of s t e e l on a s h i p . Half d r u m s c o n t a m e d g r o w i n g n a t i v e v e g e t a t i o n to f r o m s n a i l arms fire but a l s o limits d e p r e s s i o n of g u n . rails and sheet m e t a l for roof re m f crement and p r o t e c t i o n . c a m o u f l a g e p o s i t i o n .

47

MILITARY ENGINEERING

I OS

Z

o a. z

u

P i c t u r e M o . 9 5 (PM 3 3 7 ) 1 4 c mb a t t e r y c o v e r i n g SOUTH P a s st o P r e v e n t c a v i n g o r s p a l l m ?

GUM, M o t e

f r ^ m

UMAM: u s e of m u z z l e

Mo. 2 ? « n of 2 - f u n r e i n / o r e m g s t e e l b l a s t .

P i c t u r e M o . 9 6 (PM 3 3 1 ) 1 4 c m GUM CAVE EMPLACEMEMT, YUKOKA, UMAM: M o t e r e a r of t u r . r . e t , b r e e c h ( c o v e r e d ) a n d t y p i c a l

s t r a t a . C l o s e i n s p e c t i o n w i l l r e v e a l a h o r i z o n t a l " d y k e "a b o u t 1 ' t h i c k j u s t b e l o w c e i l i n g l i n e .

r o c k P i c t u r e M o . 9 7 (PM 4 8 3 ) ' i a c m

T h i s w e a p o n i s t h e o n l y l a r g e M i s s i o n : t o f i r e o n s u r f a c e

v i d e i c a m o u f l a g e f o r P o s i t i o n

AA GUM IM CAVE EMPLACEMEMT, UDOT: a r t 1 l l e r y w e a p o n l o c a t e d o n UDOT­

c r a f t t o t h e n o r t h . T r e e s p r o ­ b u t w e r e r e m o v a b I t b y f i l l i n g .

Z

Plans called for each island to be self sufficient defensively. However, o z mutually supporting artillery fires were planned between adjacent islands. A part of each island1s forces was to be held out specifically as a mobile reserve for island-to-island amphibious movement and counterattack* Indications are that the

— Japanese would have made a concerted effort to defend strongly only the four "Season UJ Islands" but the general plan recognized also the importance of movement of forces to z meet any possible landing. -I

No general distinctions were noted in the organization of the ground in com­o paring the defenses of DUBLON, MOEN, UMAN, and FEFAN. Weapons were placed to pro­vide a concentration of fire from divisional weapons on all possible landing beach­es. Beaoh pillboxes provided bands of interlacing grazing fire, usually in two directions from each along the beach. These beach positions provided also the

-I automatic weapons coverage for the inshore minefields and for Inshore and beach ob-O stacles. In general, observation from the beach positions was adequate for the wea­

pons emplaced. Concealment was achieved by natural growth, transplanted as neces­5: sary, and the use of wire screens garnished with natural materials. As one pro-XL gressed inland, the difficult terrain offered many problems to weapons placement. ac The Japanese recognized the dead spaces in fields of fire of automatic weapons and

also their limited fields of view in the abundant tropical growths. In most in-z stances they attempted to cover these defiladed areas by rifle and mortar fire. In o comparison with the Japanese defenses found on CHICHI JIMA, TRUK defenses had less CO fortification of inland areas, less excavation work and less connecting of positions. UJ Wooden platforms were constructed for OPs atop the principal mountain peaks but their

complete lack of cover and concealment would have limited their use considerably as soon as hostile planes and surface craft approached within effective ranges.

The primary missions of the 250 men placed on the reef islands were obser­vation and the construction of dummy positions. Their communications were by under-

CO water cable and radio to the main islands. UJ

On the whole, organization of the ground for the defense of airfields followed z accepted US doctrine. At the typical MOEN No. 1 Field and the adjacent MT. KONGO hill mass, the defense force consisted of about 500 Army personnel and 300 Naval personnel of a special navy landing party. The Naval unit provided grazing MG fire over the airfield, its dispersal areas, and over the beaches adjacent to the field. Army 47mm. auto-cannon in pillboxes covered possible road approaches and, in two places, alternate positions were noted. Two platoons were held in reserve in caves

naif way up the slope* Caves and dugouts provided cover for nearly every weapon. A large number of small air raid shelters were found scattered throughout the area. Battalion officers stated that even with these many shelters, some 20 men were killed there as a result of US bombing. Extensive communication trenches in ex­cellent condition linked positions on the lower slope. In the rocky areas near the summit, tunnels connected the cave positions. Some of the machine guns were placed so as to fire from caves on low flying aircraft only. No anti-aircraft artillery was located in the immediate vicinity but batteries on adjacent islands could provide ack-ack support. Unit officers stated also that, seventy knee-mor­tars were available in the MT. KONGO area in addition to those weapons shown on the weapons disposition map.

FORTIFICATIONS.

Permanent: Lt Col YAMAMOTO, Chief of Staff, Japanese 52nd Division, stated there were no permanent fortifications when his unit arrived at TRUK in January, 1944. An extensive fortification program was started then with the construction of pillboxes and blockhouses on the seashore as first priority. For concrete con­struction they used a 1:2:4 mix with beach sand and crusher-run basalt rock. Steel reinforcing bars 20 mm in diameter were placed 25 cm apart in the conventional right angled grid* Typical pillboxes found on the beaches are shown in Picture Nos. 86, 87, 88, 89, and 90* Picture No. 91 shows an ant1-ricochet type embrasure noted at several emplacements. The idea was to reduce the number of email arms ricochets glancing into the emplacement. Some pillboxes were constructed so near the water, or so low in it, that seepage or flow through the embrasures flooded the interiors. Eventually the lack of cement halted concrete construction* At the time of the inspection several stockpiles of reinforcing steel remained at various locations on several islands*

Nearly all of the larger naval artillery pieces, except anti-aircraft batteries, were placed in caves or dugouts typical examples of which are shown In Picture Nos. 92, 93, 94, 95, 96, 97, and 101. Figures 11 and 13 show details of typical con­nected cave emplacements. Picture Nos. 98 and 105 show an exception to the usual emplacement in that this weapon was located only 50* from the seashore on LIGHTHOUSE Hill, MOEN. Typical accessories, such as observation posts and ammunition storage facilities, for artillery pieces located in caves are shown in Picture Nos. 99, 100, 102, and 104.

48

Picture No. 98 (PM 261) 12cm GUN EMPLACEMENT,MOEN: Mission: to Provide supporting firein? DUBLOh. Note angle embrasure and rearconcrete roof, 2 thick, catuouf lagei with

LIGHTHOUSE on troops

exit. Re xnf native grass.

HILL assault'

or.ced

Picturefigurephoneposit

No. 9 9 (PM 333) OP, 14cm GUN BATTERY, of G-eneral DAVIS for size. C ommun ic at and voice tubes (1 to left, 9 to right) 1ons.

UMAN: Note i on was by

to the gun tele-

PictureRangeCavehand

No. 100 (PM 332) RANGE FINDER, 14cm GUN BATTERY, finder in operating position with canvas cover in provided cover while m storage Position. Retraction propelled cart on small railway track.

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Picture No. 101 (PM 336) 14cm GUN(U-8), UMAN: No. 2 gun of Picture No. 102 (PM 444) ENTRANCE, 12cm GUN EMPLACEMENT, PARAM: Picture No. 103 (PM 446) 6" ARMSTRONG CD BATTERY, P4LLE O s-gun battery. Note rear of turret and use of steel rein- Note coconut log shoring an.' use of steel railway rails as roof Timber magazine in niche off tunnel c onnect ing pieces-forcing r.ods and mesh to prevent caving and wooden shield to beams. Entrance gives access to tunnel to gun position shown prevent spalls falling from overhead during firing. in picture no. 93.

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P i c t u r e N o . 1 0 4 (PM 3 3 ^ ) AMMUNITION S T O R A G E , 1 4 c m GUN B A T T E R Y , P i c t u r e N o . 1 0 5 (PM 2 6 2 ) E N T R A N C E TO 1 2 c m GUN E M P L A C E M E N T , P i c t u r e V o . 1 0 6 (PM 4 4 7 ) 6 " ARMSTRONG CD GUN B A T T E R Y , P O L L E : UMAN: T y p i c a l c a v e s t o r a g e p o s i t 1 o n . P o w d e r c a n s e m p t i e d L I G H T H O U S E H I L L . MOEN: N o t e c o c o n u t l o g r o o f s u p p o r t , s h a l l o w I n c l i n e d s h a f t l e a d i n g f r o m t u n n e l c o n n e c t i n g p i e c e s a n d m a g -u n d e r s u r r e n d e r t e r m s . e a r t h o v e r h e a d c o v e r , a n d d r y m a s o n r y s i d e w a l l r e v e t m e n t . a z i n e s . T o r i g h t o f m a n ' s f e e t t h e r e w a s a s u m p f o r c o l l e c t i n g

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S T O R A G E , 2 0 c m CD B A T T E R Y , s t - i e l d o o r s , a n d e a r t h

P i c t u r e N o . 1 1 1 (PM 3 4 5 ) AMMUNITION S T O R A G E , B A T T E R Y , UMAN: N o t e h e a v y c o n c r e t e a r c h e d roof,c e s s e d d o o r w a y , e l e v a t e d d e c k , a n d e a r t h c o v e r .

r e P i c t u r e N o . 1 1 2 (PM 3 5 ° > O P , l ^ m m B A T T E R Y , UMAN: T h i s s h e l t e r h o u s e d t h e b a t t e r y ' s BC s c o p e . S t e e l a n q l e c o l -u m n s s u p p o r t 1 4 " t h i c k c o n c r e t e roof. E n t r a n c e b y c o v ­e r e d P a s s a g e w a y f r o m r e a r .

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E x c e l l e n t h a n d c r a f t i n s t a l l a t i o n s h o w n m P i c t u r e N o . 1 1 1 . s h o w n i n t i m b e r , s t o r a g e s h e l v i n g a t

N o t el e a d

r o c k a n d e a r t h t o n e a r b y c a v e

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T r a c k s i n b a c k ­

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P i c t u r e N o . 1 1 6 (PM 4 0 1 ) 6 - G U N , 1 2 c m AA BATTERY, FEFAN: 2 of t h e 6 g u n s a r e d i s t i n g u i s h e d e a s i l y ; c l e a r e d a r e a s h o w s e m p l a c e m e n t l o c a t i o n s . I n d i v i d u a l s a r e s t a n d i n g o v e r c o m ­m u n i c a t i o n s r o o m .

Pic ture No. n g (PM 480) BTRY CONTROL, 12cm AA, EOT: Type 2 f ire director (foreground); open pit (observer); r e m o t e controls for 150cm searchlight (bac kground); BC 's post and scope (left bac kground).

P i c t u r f i N o . n y (PM 4 0 2 ) 1 2 c m AA GUN, FEFAN: Gun m o u n t e d o n t r u n e a t e d c o n e - s h a p e d s t e e l f o u n d a t i o n p e d e s t a l 1 m e t e r h i g h . U n d e r g r o u n d s h e l t e r d i r e c t l y b e h i n d e l e v a t i n g g e a r .

Picture No. 120 (PM 63) ENTRANCE DIVISION BATTLE CP, DUBLON: Note inter 1 or baffle wall and steel door.

z

P i c t u r e N o . 1 1 8 (PM 4 0 4 ) AIR RAID SHELTER, 1 2 c m AA BAT TERY, FEFAN: T i m b e r s f o r s u p p o r t i n g r o o f a p p e a r e d t o CD

b e of m s u f f i c l e n t s t r e n g t h a n d P o o r l y s e l e c t e d . N o t e r o c k a n d e a r t h o v e r he a d

Picture No. 121 (PM 265)A/F NO. 1: Pillbox c onstfilled

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LIGHT MG PILLBOX ON BEACH, MOEN ruct i on of cemented stones over

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Picture No. 122 (PM 61) CG's AIR RAID SHELTER, 52ND DIV- Picture No. 123 (PM 62) DIVISION BATTLE CP, DUBLON: P i c t u r e N o . 1 2 4 (PM 4 8 1 ) 1 2 c m AA GUN, E O T : A l l 4 g u n s of ISION BATTLE CP, DUBLON: Photo shows the niche where the Interior view. Debris marks end of uncomp letei tunnel t h i s b a t t e r y w e r e e m p l a c e d m o p e n p i t s w i t h c o n c r e t e r e -General reclined during air raids. Excavation m solid Form nails imbedded in ceiling a definite overhead v e t t e d w a l l s . V a i l s h a d n u m e r o u s s h e l v e s f o r " r e a d y " rock approximately 20 meters underground. hazard. a m m u n i t 1 o n .

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MILITARY ENGINEERING

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Typical of the coastal defense gun emplacements found at TRUK are those forco the 4-gun battery of 20cm. pieces on LIGHTHOUSE Hill, Picture Nos. 107, 108, 109, 110, and the 3-gun, 155mm. battery, south UMAN, Figure 12 shown also in Picture Nos. Ill, 112, 113, 114, and 115.

o Figure 14 shows a 6-gun, 12cm., AA battery located on MT. NISHIKI, FEFAN. This battery position was landscaped very neatly and gave the over-all appearance of a public park. Picture Nos. 116, 117, and 118 are of the same battery. A sim­ilar 4-gun, 12cm. AA battery located on EOT is shown in Picture Nos. 119, and 124.

Figure 15 depicts the permanent type battle CP of the Japanese 52nd DivisionO on DUBLON. Picture Nos. 120, 122, and 123 are of this same installation. It was used during the periods of actual US air and British naval attacks only. In gen­eral the tunnel is 10 meters underground in solid rock with an arched concrete roof. Living quarters for the commanding general ana his staff are provided in the shelter and storage and communication facilities in rooms off the main tunnel. Overhead electric lighting provided illumination. One hundred men labored daily

z for six months to construct this CP.

O to Figure 18 shovrs the Navy battle command post at the summit of MT, TOLOMEN, UJ DUBLON. The parallel tunnels have exits on both sides of MT. TOLOMEN. The en-CO trances are roughly 20 meters underground with overhead cover of solid rock in-Z creasingly thicker as one proceeds towards the center of the mountain. Work was

started in July, 1944, and completed in July, 1945. Some 31,000 man hours of labor were required to excavate the 2,100 cubic meters of solid rock. For this

UJ excavation of a 380 cfm-lOO# compressor, belt driven by a vertical diesel engine, CO was located 100• down the slope. The air was piped uphill to three rock drillsLU

at the worksite. About 6,300 kilograms of dynamite were required for blasting the Z rock. Spoil was carted by hand from the tunnel in small cars or wagona on indus­

trial railway track. Extensive communication facilities were provided in the in­$ stallation. The reported capacity of the two tunnels was 600 men. The use of

power tools when available to speed construction is typical of all naval forti­fication work at TRUK.

SOUTH BEACH, UMAN: This Picture No. 127 (PM 3q6) INTERIOR OF AIR RAID SHELTER, MT. water) was to obstruct NISHIKI, FEFAN: Note notched timber construction and en­ifa 11 covered by e n f i - trance in backg round. Except1ona I ly heavy timbers used to directions. support sleeping mats.

Figure 16 shows the plan of a battalion command post near the summit of MT. FUOUKANAN, DUBLON. Again the excavation was in solid rock with thick overhead protection. Figure 17 shows a battalion command post found on MT. UBUN, FEFAN.

Field Fortifications: In general no unusual field fortifications were found at TRUK. Many of the coconut log and earth emplacements and shelters were de­stroyed after the surrender and prior to arrival of the Study Group. Picture Nos. 121, 125, and 127 are typical examples. Infantry units constructed their own fortifications from local materials and, generally, by hand labor. Picture No. 129 of the interior of a 47mm. AT gun emplacement at the 4th Fleet Road crossing, DUBLON, shows where a portion of the roof has collapsed by reason of the rotting of the coconut logs used to shore it. Entrenchments noted were of good design. No revetment work was needed to prevent cave-ins on the two communication trenches observed.

OBSTACLE CONSTRUCTION TYPES. (For locations see Maps in PART TWO.)

No inshore obstacles were observed, they were removed shortly after the sur­render, but It was reported that various steel rail anti-tank and anti-boc?.t ob­stacles had been emplaced. These obstacles were not completed when hostilities ceased.

The only type of beach obstacle observed was a rock wall, anti-personnel and anti-walli£ator"~, approximately 51 high and 81 wide at the base. Picture No. 126 shows an example of tills type obstacle. Pillboxes were placed so as to cover with enfilade machine gun fire both faces of the wall.

No anti-personnel or anti-tank mines were found inland and it was reported that there had been none there. However various anti-tank obstacles, located to take maximum advantage of the terrain, such as walls and trenches, were found. Figure 19, and Picture No. 128 show an anti-tank wall constructed of earth and faced with rock-filled oil drums across a low flat area near DUBLON Town.

52

FIGURE NO.II 15 CM GUN POSITIONS,NORTH

SECTION OF TOL ISLAND

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I I

GENERATOR 25KVA

3T0N WATER TANKS 'i * O <

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FIELD OF FIRE 160* MAX RANGE- 3000 M.

GUN'S AMMUNITION

DUMP

FIRE CONTROL AMMUNITION*1

DUMP o

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TYPE 41- 15 CM. GUN MAX. RANGE- 13,600 METERS

FIELD OF FIRE-45*

120* z

25MMx2 MAX. RANGE-3000 M FIELD OF FIRE-135

SEE DETAIL NO. I o

l3MMxl MAX. RANGE-2500 M.

FIELD OF FIRE-135"

\ SEARCHLIGHT SIZE-90 CM MODEL-TYPE-96 RESERVE

AMMUNITION DUMP

SEE DETAIL NO. 2 RANGE FINDER TYPE 14 3.50 M.

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PROTECTIVE CAVE FOR RANGE FINDER 3RD YEARl MODEL

15 CM.GUN 140'

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7.7 MM x I MAX.RANGE-2004 M FIELD OF FIRE'14

l3MMxl FIELD OF FIRE

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7.7MMxl ^ FIELD OF FIRE 120'

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A FIRE CONTROL •0- RANGE FINDER - ~ HMG -— LMG

GENERATOR

TYPE 96,110 CM SEARCH LIGHT

RESERVE AMMO DUMP

FIRE CONTROL CENTER

CAVE FOR SEARCH LIGHT

270°

FIGURE NO 12 155MM COAST DEFENSE BATTERY

UMAN ISLAND

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MAIN AMMUNITION 1 DUMP ' A SECONDARY ^MUNITION DUMP

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FRONTAGE

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HEIGHT THICKNESS OF CONCRETE EARTH MOUND

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53

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90 CM SEARCHLIGHT

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AMMUNITION STORAGE

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14 CM GUN BATTERY-(SOUTH) PART OF UMAN ISLAND)

SHALLOW DRAIN

DRAINAGE DITCH

x — TELEPHONE LINE

Y — VOICE TUBE

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STORAGE

FIGURE NO. I4-(FEFAN ISL)

ANTI-AIRCRAFT BATTERY EMPLACENTS

ANTI-AIRCRAFT GUN MACHINE GUN (13mm)

V777\ BURIED BUILDINGJUNNEL

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CROSS SECTION A-A

FIGURE NO. 15- ARMY

DIVISIONAL COMMAND POST

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FIGURE NO. 16

INFANTRY BATTALION

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55

NOTE-® TO ® IS 35 METERS

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FIGURE NO. 17

34IST BN. C. P. MT. UBAN-FEFAN ISLAND

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NAVAL BATTLE C.P CAVES, DUBLON

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OPERATIONS a STAFF RM. CHIEF OF STAFF

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ELEVATION OF TUNNEL ENTRANCE 880'

FIGURE NO. 19

TYPICAL ANTI-TANK OBSTACLE NOT TO SCALE

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56

P i c t u r e N o . 1 2 8 (PM 1 0 3 ) AJT W A L L , D U B L O N : In a l o w a r e a

a p p r o x . 1 0 0 y d s m l e n g t h , 8' a c r o s s at t o p a n d 2 0 ' at

b a s e . S l o p e g r a d e d t o 1 on 1 on o p p o s i t e s i d e of e a r t h

f \ l i e d d r u m s .

P i c t u r e S o . 1 3 1 (PM 4 4 9 ) 9 0 c m S E A R C H L I G H T , T O L : T y p i c a l h a n d c a r m o v e m e n t f r o m c a v e s h e l t e r t o o p e r a t i n g p o s i t i o n N o t e t r a c k f i t t i n g f l u s h w i t h c o n c r e t e f l o o r a l s o v o i c e t u b e s a n d t e l e p h o n e on c a v e w a l l s .

P i c t u r e N o . 1 2 9 (PM 1 2 5 ) 4 7 m m G U N E M P L A C E M E N T , 4 T H F L E E T C R . D U B L O N : S h o w i n g c a v i n g of o v e r h e a d w h e n c o c o n u t l o g s u s e d a s s h o r i n g r o t t e d a w a y .

P i c t u r e N o . 1 3 2 (PM 2 5 6 ) 1 5 0 c m S E A R C H L I G H T S H E L T E R , L I G H T ­H O U S E H I L L , M O E N : S e a r c h l i g h t w a s m o v e d to o p e r a t i n g p o ­s i t i o n s h o w n m P i c t u r e N o . 1 3 5 by h a n d c a r on n a r r o w g a u g e t r a c k . H ot e c o n c r e t e r o o f a n d r o c k s i d e w a I I f a c i n g .

P i c t u r e N o . 1 3 0 (PM 3 4 8 ) 1 5 5 m m C D G U N , U M A N : P i c t u r e t a k e n at

2 5 y d s . s h o w s ab u n d a n t n a t u r a l c a m o u f l a g e g r o w t h on rev e t m e n t

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a n d - b l a c k m o t t l e d t u r r e t b l e n d e d w e l l i n t o g r e e n b a c k g r o u n d .

P i c t u r e N o . 1 3 3 (PM 5 5 8 ) N O R T H P A S S , f O N E L I K 9 0 c m S e a r c h l i g h t s h o t o u t by U S s t r a f i n g f i r e .

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P i c t u r e No. 1 3 7 (PM 3 3 4 ) R A N G E F I N D E R , 14cm B A T T E R Y , UMAN: P i c t u r e N o . i 3 8 (PM 3 5 3 ) E X T E R I O R VIEni 3 7 m m AT GUN P I L L B O X , P i c t u r e N o . 2 3 9 (PM 2 3 9 J S E A P L A N E B A S E , M O E N : S h o w i n g one of N a t u r a l c a m o u f l a g e . A b u n d a n t g r o v t h of v i n e s f r o m v e r t i c a l UMAN: C l o s e i n s p e c t 1 on r e v e a l s e m b r a s u r e i n d i c a t e d by mar- s e v e r a l c a r s m o u n t ing p a i n t e d e a r t h f i l l e d b o x e s s u r m o u n t e d by c l i f f c o n c e a l e d cave m o u + h . Vines were pushed a s i d e e a s i l y g i n a l a r r o w s . E x c e l l e n t n a t u r a l c a m o u f l a g e . See P i c t u r e gas d r u m s s p r o u t i n g n a t u r a l c a m o u f l a g e . Cars c o u l d be r o l l e d to P e r m i t i n s t r u m e n t to be r o l l e d into ope rat ing p o s i t i o n . N o . go for i n t e r i o r v i e w .

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SEARCHLIGHTS. MINES. MINE WARFARE. BOOBY TRAPS. EXPLOSIVES AND DEMOLITIONS. z

The only army searchlight unit on TRUK was the 4th Battery, 25th AA Unit. Inshore and beach mine fields are shown on Maps in PART TWO. Mines have been Five Type 93, 150cm, searchlights were utilized, four of them were emplaced in removed in accordance with surrender instructions. No inland mines were noted. CO open pits on DUBLON and one on FALO. For location of these searchlights see (See Obstacles)

a Artillery Disposition Map, Power for searchlights was furnished by truck mounted generators. One Type 90, sound detector, was used in conjunction with the search- The usual dynamite explosives were used while stocks lasted. After exhaustion lights. of the normal types, explosive charges from aerial bombs were used to continue z

CO blasting work in connection with fortifications and quarries. (See Picture No, 163 Table A-2 shows the type and number of Navy searchlights at TRUK, Picture for preparation of improvised charges for quarrying). Indications are that dyna-LU

Nos. 131, 132, 133, 134, and 135 show typical searchlight emplacements. The Artil-Z mite and dynamite caps were often poor and faulty. Very probably this was due to lery Disposition Map shows the location of the naval searchlights on the various damp storage. islands, o

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TABLE A-2 CAMOUFLAGE.

Island

Inventory of Searchlights on TRUK (Nav.v)

Battery Type Diameter(in cm.) Number

No attempt was made to conceal the larger permanent service Installations, Army or Navy, by camouflage. Field units utilized terrain, natural materials, and camouflage nets for concealment. The general policy was to cover the tops of pill­boxes with earth and sod as shown in Picture No. 138. Picture No. 130 shows a 155cm, gun at 25 yds. Entrances to positions were hidden by planting trees, usual­ly banana, and by hanging camouflage nets. Communication trenches and barracks roofs were covered with coconut palm fronds. Some disruptive painting was noted around embrasures. The Japanese said they planned to use logs In the construction of dummy gun positions along the beaches but had not done so by the cessation of hostilities. In the event of attack it was planned to use the limited supply of chemical smoke (See Army Ammunition Inventory) to draw fire to unimportant areas and to cover local counterattacks. Picture No. 137 shows natural camouflage of the entrance to a tunnel containing the range finder for the 14cm. guns on UMAN.

1 See Picture No. 139 for ambitious scheme for concealing an entrance to a cave used

MOEN MOEN

MOEN MOEN DUBLON FEFAN

FEFAN

7cm, AA 12cm. AA

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The Japanese insisted they had no plans or equipment for offensive chemical warfare.

In defensive chemical warfare they emphasized the use of Individual equipment such as gas masks and gas clothing. Only one gas proof shelter was completed though four others were in process of construction. Figure 20 shows detailed plans for the one shelter they finished. The active purifying chemical was copra char­coal. Tables*A-3, and A-4 show chemical warfare equipment on hand at the end of the war.

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Picture yo. 140 ff# 406; J/4rffJ? COLLECT­ION, FEFAN: Example of the e f f o r t the Japanese made to c o l l e c t all a v a i l a b l e w a t e r . Small m e t a l t r o u g h s c o l L e c t e i the seepage from the t u n n e l i n t e r i o r and c a r r i e d it to a c o n c r e t e s t o r a g e tank in t u n n e l f l o o r .

Picture No. 141 (PM 3 9 8 ) 2 $ k v a G E N E R A T O R , FEFAN: This d i e s e l d r i v e n g e n e r a t o r fur­nished power for one T^cm s e a r c h l i g h t and a p p e a r s to be the s t a n d a r d power unit at TRUK for t h i s s e a r c h l i g h t .

P i c t u r e No. 142 (PM 4 0 3 ) C O M M U N I C A T I O N CENTER SHELTER, 6-GUN AA BATTERY, FEFAN: U n d e r g r o u n d room c o n t a i n e d i n t r a b a t t e r y t e l e p h o n e s w i t c h b o a r d , d a t a t r a n s m i s s i o n e q u i p m e n t , and r a d i o for c o m m u n i c a t i o n to D U B L O N . L a d d e r s lead t h r o u g h 24" c o n c r e t e .

P i c t u r e No. 143 (PM 4 8 2 ) 4 O k v a G E N E R A T O R E O T : This i i e s e l d r i v e n g e n e r a t or fur­n i s h e d power for one 150cm s e a r c h l i g h t , one fire d i r e c t o r and d a t a t r a n s m i s s i o n s y s t e m for f o u r 12cm AA G u n s . S w i t c h ­board m b a c k g r o u n d .

Picture No. 144 (PM 33SJ TYPICAL LATRINE UMAN: L a t r i n e c o n s 1 s t e d of two simple frame s t r u c t u r e s , one h o u s i n g the u r i n a l and the other for f e c a l m a t t e r (Picture No. 1 4 6 ) . Small w o o d e n box was for d i s ­i n f e c t a n t used to wash hands a f t e r u r i n ­a t i n g .

P i c t u r e No. 145 (PM 3 3 9 J I N T E R I O R OF URINAL, UMAN: I n t e r i o r of latrine shown m Ptctur". No. 1 4 4 . Wooden t r o u g h em­ptied into a m e t a l t r o u g h which ran d o w n h i I I for 6' where the und 1 luted urine s p i l l e d over the open g r o u n d .

P i c t u r e No. 146 (PM 3 4 0 ) T Y P I C A L LATRINE UMAN: Note c o m p l e t e lack of s c r e e n i n g . C h i n a " s q u a t t e r " for e xc r.eme nt was p r o ­vided with loose f i t t i n g w o o d e n c o v e r (barely d i s c e r n i b l e leaning a g a i n s t far w a l l ) .

P i c t u r e No. 147 (PM 3 4 2 ) PERMANENT TYPE L A T R I N E , UMAN: This latrine was used by e n l i s t e d men of the 155mm gun battery located on S o u t h UMAN. Note s m o o t h c o n -c ret o. f i n i s h on u r i n a l at r i g h t . Doors at left led to i n d i v i d u a l box s e a t s over a p i t .

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P i c t u r e N o . 1 4 8 (PM i 9 9 ) WATER STORAGE TANKS, MT. N I S H I K I , FEFAN: T h e s e t w o t a n k s f o r c o l l e c t i n g r a i n w a t e r h a d a s t c r a g e c a p a c i t y of «> t o n s e a c h . T a n k s h a d s h e e t - m e t a l l i n i n g s a n d r o o f s .

Picture No. 151 (Pm 14?) TROOP SHELTER, 1 5 5 m m BATTERY, UMAN: Note grass floor sleeping mats, mosquit0 nets, electric I tght ing, and, a rarity, glass windows.

P i c t u r e N o . 1 4 9 (PM 4 8 4 ) TROOP SHELTER, UDOT: S t r u c t u r e c o n ­s i s t e d of s i m p l e w o o d e n f r a m i n g w i t h t h a t c h e d g r a s s s i d e w a I I s a n d c o r r u g a t e d s h e e t m e t a l r o o f . N o t e o v e r h e a d s h e l v e s f o r s t o r i n g c l o t h i n g a n d e q u i p m e n t . R e p o r t e d o c c u p a n c y 1 0 m e n .

P i c t u r e No. 2 5 2 (PM 4 5 0 ) G E N E R A T O R CAVE. CD B A T T E R Y , NORTHT O L : Prime mover, and g e n e r a t or. r i g h t ; s u i t c h b o a r d , c e n t e r ;w o r k b e n c h , l e f t .

P i c t u r e N o . 1 ^ 0 (PM 4 5 2 ) NAVY GUN CREW BARRACKS, NORTH TOL, B a r r a c k s f o r 1 4 0 m e n . T h i s a r e a h a d n o t b e e n d i s t u r b e d b y US b o m b i n g .

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TABLE A-5

Lj.st of Army Chemical Warfare Materiel

UNIT QUANTITY NOTE

Item Item Set

40 210 18 A number of hygrothermographs are

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Set 40

TABLE A-4

List of Navy Chemical Warfare Materiel

ARTICLE UNIT

Gas Masks Each Containers and Fittings

for Gas Masks Kit Light Gas Clothing Each Gas Clothing Each Gas Detector Each Gas Covers Each Mk-3 Decontamination Kit Kit Mk-4 Decontamination Kit Kit Mk-5 Decontamination Kit Kit Oxygen Gas Masks Each Oxygen Generator Each

QUANTITY

11,071

79 2,064 161 90

9,941 159 395 100

5 20

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u Canisters (for exchange) Item 487

z Type 96 Complete Gas Set 1,105 FIELD UTILITIES. Protective Clothing

Type 96 Light Gas Set 14,481 Protective Clothing Except where dispersed Army units had rainwater cisterns, springs, or shallow

Gas-Protective Shoe Set 150 wells, water supply was primarily a Navy function. (See General Construction). Z Cover (A) Rainwater was collected by means of systems of troughs, gutters and pipes from

Gas-Protective Shoe Set 420 nearly every roofed building, hut, and shack. Normal precipitation in this area Cover (B) is sufficient to supply small isolated groups but inadequate for such concentrated

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Protective Clothing iorated and cannot be used, only have become a serious problem In the event that hostile troops held the surrounding lowlands. The caves were too near the relatively small peak or summit to tap sub-the reserves are shown.

Gas-Protective Coat Set 47 CO Observation Eye-Glasses Set 896

Anti-dim Plate Set 410 Repair Kit for Gas- Set 10 Protective Clothing

terranean basins or flows. By collecting rainwater, the Japanese reduced consider­ably their need for filtering and purifying equipment. Boiling was prescribed as the approved standard method for purifying water for drinking. The army had 472 cases of amoebic dysentary in 1944 and 266 cases in 1945. In view of the widespread use of night soil for fertilizing, these cases should not be attributed exclusively to impure drinking water. Picture No. 148 shows two typical 5 ton capacity rain­water storage tanks at an anti-aircraft battery on MT. NISHIKI, FEFAN. Picture No. 140 shows collection of water dripping from the interior of a cave on FEFAN. The Japanese claimed that US bombings interfered with their search for additional water sources and with their further exploitation of those they had.

The main installations were dependent upon a central source of electrical power. Smaller units, such as anti-aircraft troops, had standard 17.5, 25, and

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Gas Medical Treatment Kit A Set 31 I— Gas Medical Treatment Kit B Set 32 40kva dlesel engine driven generators. Picture Nos. 141 and 143 show typical equip-

Gas Medical Treatment Kit C Set 208 ment. In nearly all cases these generators were in unprotected frame buildings lo-Mark 1 First Aid Kit Set 102 cated near searchlights. Some truck mounted generators were available for use with Mark 2 First Aid Kit Set 287 searchlights.

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Gas First Aid Kit Set 29 Gas Masks for wounded Item 38 In general, there were no enforced sanitation or refuse disposal regulations. Personnel decontamination Item 18,000 Individuals relieved themselves wherever they pleased. Flies were everywhere in

Pouch abundance and especially near latrines. Picture Nos. 144, 145, and 146 show a CO Decontamination Pouch Item About Since their use has been discon- latrine used by naval officers of the 155mm. gun battery on south UMAN. The most Z 25,000 tinued it is difficult to give elaborate field latrine found was that for the 155mm. gun crews on UMAN. (See Picture UJ No. 147). Fecal matter from oil drum type latrines was used freely as "night soil" accurate figures* u. A Medical prescription Item 550 or fertilizer and any remainder was buried. UJ a B Medical prescription Item 2,300 Hi Eye lotion Item 1,100 CO UJ Nose lotion Item 1,100 Z Chlorine suction tube Item 500

This table gives the total of all chemical warfare material for the various Army units at TRUK.

This table is based on reports for July, 1945. Because of bombing, depreciation, etc., the present totals will be somewhat different.

Housing for dispersed units and small groups was, by our standards, highly unsatisfactory. Overcrowded shacks of salvaged materials with twigs and branches for flooring were standard. No screening was observed on any of the islands. Some mosquito bars were noted however. Picture Nos. 149 and 150 show some of the better type of shelters observed.

Usually the shelters for signal communications facilities were rooms off the main tunnel In a cave. Picture No. 142 shows a signal communication center room for AA battery.

62

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t h e y w e r e u n l o a d e d . A l l t i r e s w e r e " s a l v a g e d " w i t h k n i v e s f o r u s e o t h e r w i s e .

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63

I

GENERAL CONSTRUCTION

ROADS. TRAIL3. AND RAILROADS.

Roads: All roads on the islands of TRUK were found to be narrow (91 to 10' wide) and were constructed, reportedly, mainly of a 6" to 10" layer of poorly graded machine crushed volcanic rock (basalt) with a clay-soil binder. Our obser­

o vations corroborated the report. In general, all roads followed the natural con-o tour of the ground; cuts or fills being used only where unavoidable, as sidehill

bench-sections on steep slopes. Meager attention was paid to drainage in the east­ern islands of the atoll. The more sparsely peopled western islands had fairly well drained roads, where there were any roads at all. The Seaplane Base and a few of the streets in DUBLON Town on DUBLON Island were paved with concrete but this was but a small fraction of the total road mileage.

The equipment used for road construction consisted of rock crushers (See Picture No. 158), trucks, hand carts, and hand tools. No graders, dozers or motor-patrols were to be found anywhere on TRUK, Two 6 cu. yd, carryalls (See Picture No, 157) were in the Transport Department1a storage yard east of DUBLON Town but the Jap­

m anese claimed they never used them because they had no tractors. The crushers were Z hand fed from narrov? gauge railway cars loaded at the quarries and pushed by hand

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railway ears. The capacity of each crusher was approximately 2 cubic meters per nour. All quarry drilling was done by hand, A typical rock crusher installation is shcv.'fi in Picture Nos, 159, 160, 161, and 162.

lifter the Japanese exhausted their supply of dynamite, they drew picric acid explosive fillers from aerial bombs, crushed it by hand (See Picture No.163), pour­ed hap-hazzard quantities into homemade paper sacks and used the variable car­tridges thus formed for blasting in their quarries, caves and tunnels.

Trails: Military installations, in the islands1 hills, as lookout posts, gun positions, air raid shelters and, later, barracks areas, were accessible by well secluded primitive trails, taking full advantage of natural cover and concealment. Trails were simple paths following easy ground contours. The steeper grades were overcome by means of crude stepd dug into the rocky earth.

Railroads: Narrow gauge railroads were used extensively for moving rock and spoil from quarries and tunnels or caves. Numbers of 3 cu, yd. tipple cars were used. Initially, these cars were drawn in trains of 12 by 50 HP gasoline loco­motives, (See Picture No. 164), After the loss of the locomotives to US bombings, hand power prevailed but advantage was taken of gravity grades for loaded cars wherever possible.

B A S E , D U B L O N : I n t e r i o r P i c t u r e No. 168 (PM 6 6 ) SUBMARINE B A S E , D U B L O S : T o r p e d o cave s h o w i n g p u r i f i e r t a n k s l o a d i n g p i e r . Note n a r r o w gauge r a i l w a y , 2 & - t o n s t i f f -

leg d e r r i c k and f l o a t i n g I r y d o c k ( b a c k g r o u n d , r i g h t ) .

P i c t u r e tfo. 1 6 9 ft* tj)•'• S&BMAR flg ^ Hand op- P i c t u r e No. 170 (PM 6 8 ) SUBMARINE BASE, D U B L O N : T o r p e d o P i c t u r e No. 171 (PM 6 4 ) SUBMARINE B A S E , D U B L O S : North e rated winches fof«2£-ton s t i f f - . l k g * ie rr 1 c h a n d l i n g loading p i e r . Note 2 ^ - t o n s t i f f - l e g d e r r i c k for h a n d - f JLC e of North Pier . t orpedoes. [• -1 \- ,, ling t o r p e d o e s . Only two l i g h t e r s could be b e r t h e d here

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POLICEMANS STATION DUBLON

FIGURE N0.22- ISLAND SUBMARINE BASE

NAKAMURA­

SHIRAHAMA

BATTERY

WATER SERVICE .TORPEDO STORAGE CAVES

|CD| AIR RAID SHELTER WATER TANKS ANTI -TANK OBSTACLES EARTH MOUND-BARRICADE

ORE NORTH\(~~

^ r HOZAN-MARlfl—<

NETON

BATTERY Y / ~ V

~^i /TAKAO MARU / \ ^-UDOT \ \ /URIKAI V^FUJI MARU J \JI>\

j T O L / EBISO-MARU YASAI ^CHUZAI

-T ^ X V-AMACHIYAN P A F

J) \\? FUKASON

/ \J> JUHO

^ - ^ HOZAN FIGURE NO.21

LOCATIONS OF PIERS (TRUK ATOLL)

FLEET. TORPEDO

SHIP REPAIR, CHARE\DUBLON

\ SOUTH TRANSPORT

AIR GROUP CHURCH

WATA\AIR DEPOT SEAPLANE BASE

BATTERY

30t

0 30 60 90 120 150 180 210 240

65

100 a 65 KVA / v GENERATORSX/"

1 ! !

SDISPENSA

TORPEDO ORDNANCE REPAIR SHOP

45 KVA GENERATO

Oe GAS

4TH SHIP REPAIR OFFICE

T E L E P H 0 N E• J REPAIR SHOP / ^ A R P E N T E R SHOP /

\y\STORE

300 T MARIN RAILVi^Y FIGURE N0.23

(NOT COMPLETED) 4TH SHIP REPAIR DEPARTMENT

FLOATING DRY DOCK DUBLON ISLAND,TRUK ATOLL LENGTH - 117 M CAROLINE ISLANDS BREADTH-16.7 M HT. OF SIDE WALL 9.2 M DISPLACEMENT IN LIGHT CONDITION 2027 T 0 10 20 30 40 BO 60 70 10 90

• = • = • SCALE IN METERS

66

GENERAL CONSTRUCTION

WHARVES AND DOCKS.

Information on wharves and docks is found in Table A-5. All facilities were capable of accommodating small craft only (5-ton lighters and 10-ton sampans). There was no storage on the wharves. Cargo was unloaded directly into trucks or carts and removed to warehouses or open storage.

There was no evidence of dredged docks. Apparently, the wharves (jetties, piers, quays, landing stages) were built out to where the water was deep enough for small craft and no attempt was made to berth large vessels alongside them. See Figure 21.

TABLE A-5

NUMBER OF CAN IT CARGO DEPTH LIGHTERS CARRY HANDLING

NAME OF WHARF ALONGSIDE ACCOM- MOTOR EQUIP- TYPE OF OR PIER (METERS) MODATED VEHICLES? MENT CONSTRUCTION

DUBLON

KOHATSU 2.5 4 Yes 12w concrete slab on ro TRANSPORT JETTY 3.5 3 Yes 2 - 3-ton Earth fill with wood en

stiff leg derricks

CHARE 4.0 4 Yes Concrete slab on rock fill.

AIR DEPOT 2.0 2 Yes 1 - 10-ton Concrete slab on rock crane fill.

NAICAI 4.0 1 Yes Concrete face around rock fill.

SEAPLANE BASE 1.7 1 Yes Concrete on rock. SHIP REPAIR 6.5 4 Yes Heavy timber. TORPEDO PIER 1.5 1 Yes 2-1-ton stiff- Rock fill and concrete

leg derrick wall. GARRISON 4.6 2 Yes Iron plate over timber,

bents and deck. FLEET 4.0 4 Yes Rock fill wood end.

MOEN

NO. 2 BASE JETTY 2.0 2 Yes Heavy timber. NAKAMURA 1.5 3 Yes Heavy timber. KAMENKO 2.0 2 Yes Piled rock. BATTERY 1.5 1 No Concrete slab on rock

fill. SHIRAHAMA 1.5 1 Yes Rock fill. POLICEMAN'S STA. 4.0 1 Yes Rock fill. WATER SERVICE 5.0 5 Yes Water dis- Concrete slab on rock

charge fill.

FEFAN

WATA JETTY 3.0 4 Yes Concrete slab on rock fill.

KATSUO 2.0 1 Yes Narrow gauge Piled rock. track SABOTA 2.0 1 No Light wood. KUKKU 1.0 1 (too narrow) Rock fill. CHURCH 0.6 None (too narrow) Rock fill.

\r •: fc

BRIDGES AND CAUSEWAYS.

Bridges: Simple stringer bridges of timber construction and limited span, 101

to 12', spanned drainage ditches and tidal openings through causeways.

Causeways: A 600' causeway, 2' above high tide, of rock and earth fill con­struction crossed the shallow bay indenting the east shore of DUBLON. The exposed faces were protected by rip-rap walls. Another causeway crossed the swampy re-en­trant on the northeastern shore of MOEN.

TABLE A-5 (Cont'd.)

NUMBER OF CAN IT CARGO DEPTH LIGHTERS CARRY HANDLING

NAME OF WHARF ALONGSIDE ACCOM- MOTOR EQUIP- TYPE OF OR PIER (KST2RS) MODATED VEHICLES? MENT CONSTRUCTION

UDOT

YASAI JETTY 1.5 1 No Piled Rock. CHUZAI JETTY 1.5 2 No Piled Rock. URIKAI 1.0 1 Yes Piled Rock.

TOL

HMACHIYAN 4.0 1 No Piled Rock. FUKASON 2.5 1 No Piled Rock. JUHO 3.0 1 No Piled Rock. HOZAM 2.0 2 No Piled Rock, wood end. ORE 3.0 1 No Concrete slab. BATTERY 2.5 1 Yes Concrete slab. NET ON 3.0 1 No Piled Rock. £31SU MARU 1.5 1 Yes Piled Rock. FUJI MARU 1.2 1 No Piled Rock. TAKAO MARU 0.8 1 No Piled Rock.

ULALU

COMMUNICATION JETTY 1.5 1 No Piled Rock.

ETEN

TAKESHIMA 4.0 3 Yes Concrete slab on rock fill.

UMAN

BATTERY JETTY 2.0 2 Yes Concrete slab on rock fill.

SCHOOL 2.1 1 Yes Rock fill. RADIO 3.0 1 No Wood.

PARAM

AIR GROUP JETTY 3.0 1 Yes Timber.

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67

-V FUEL OIL TANK FARM

AND OIL SUPPLY PIERS

.NOT TO SCALE NOTE

I OPERATION OF TANK FARM CEASED APRIL 1944, DUE TO EXTENSIVE DAMAGE FROM BOMBING

2 IO>UNDERGROUND OIL LINE 3 EARTH OYKES AROUND ALL TANKS 4. ALL TANKS RIVETED, STEEL PLATE CONSTRUCTION

FIGURE NO. 26A

o z

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CO NANKO DOCK Q

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INSTALLATIONS OF 4TH MUNITION DEPT 30 JUNE .943

©SUPPLY OFFICE - 4th MUNITION DEPT

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FIGURE NO. Z5

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to OIL-TANK uu (CONCRETE) to Z

54 63 45M MAST

WARE HOUSE GENERATING ROOM o (RICE)Z

TRANSMITTING

4th COMMUNICATION UNIT TRANSMITTING STATION

DUBLON IS, TRUK ATOLL, CAROLINE ISLANDS

NOTES

I.NOT TO SCALE ? ALL BUILDINGS WOOD CONSTRUCTION 3 BUILDING AREAS INDICATED IN SO METERS

• 45 M MAST

FIGURE NO 24

(60 KVA)

351

ROOM

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194

BARRACKS TRANSMITTING ROOM

COOKING HOUSE

36 BATHING ROOM

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I

GENERAL CONSTRUCTION

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Picture So. 182 (PM H4) NANKOPicture No. 181 (PM 86) NANKO DOCK AREA, DUBLON: View inland filled pier shown was majorshowing dry rtorage Left, and cold storage, center and right. at TRUK.Z Photo shows 1 / 9 of former m s t a LLat ion whirb remained oper­

able after US bombing.

INSTALLATIONS. Z

DUBLON;

Submarine Base-The submarine base layout is shown in Figure 22. It was z equipped fully to provide supplies, munitions and extensive repairs to a sizeable

submarine force* Base working crews were quartered in two-story frame barracks with additional housing facilities for four submarine crews* Both compressed air

to and electric torpedoes were adjusted here at the rate of 18 to 36 man-days per tor­pedo. Torpedoes were stored then in a frame building surrounded by an earth revet­ment. Complete machine shops were established in typical frame buildings. After the initial US bombings caused serious loss of equipment, all remaining shops, storage and working areas were removed to and installed in an extensive cave system o nearby. Work in the caves was hampered by adverse working conditions, dampness,

ac standing water, and foul air, Equipment for generating oxygen and storing it in cylinders Is shown in Picture Nos. 166 and 167. Torpedoes were transported by nar­row gauge rail cars from cave storage to submarine base pier (See Picture No. 168) and there loaded aboard lighters by a 2^-ton stiff-leg derrick. The pier and fac-

O ilities are shown in Picture Nos. 169 and 170. The floating drydock of the adjacent ship repair base was used for major submarine repairs also. Picture No. 171 shows $h north pier of the submarine base.

3 N, a: 4th Ship Repair Base-This base was equipped to make minor repairs to all »— ships and major repairs and adjustments to vessels up to and including the destroy-Z er and submarine classes. The base was operated by 1,000 workers of all required

skills, trades and crafts. All structures, Including one-story barracks, shops and o</> warehouses, were of wood construction on concrete decks or sill walls. Only the UJ two-otory barracks had wood decks on concrete piers elevated for dryness. All ship CO repairs were accomplished while vessels were anchored in the lagoon. This required Z the use of many tugs, barges, cranes and lighters. Two 100-ton barges, one equipped

with a 40 HP compressor and a 45kw generator for electric welding machines shown in Picture No. 165, the other a deck barge used for transporting heavy loads (as gun tur­rets), were available. A 30-ton self-propelled floating crane was used in con-

en Junction with the drydock which lacked crane facilities of its own. The other com-UJ ponent parts of the base are shown in Figure 23. The principal items were: Z

A substantial machine shop was reported to have been equipped fully with 20 engine lathes, several heavy duty drill presses, moulding and punching equipment, milling machines, shapers, oxygen generating equipment and all pertinent hand tools. After US bombing attacks, about one fourth of this equipment was sal­vaged and installed in a nearby cut-and-cover shelter which provided the usual ex­tremely poor working conditions. (See Picture No. 172). Lathe operators and mach­inists stood on duck boards to keep out of the standing water. The atmosphere was stale and damp in spite of the ventilation ducts or pipes to the air above.

DOCK AREA, DUBLON: Rock Pictur.e No. 183 (PM 85) NANKO DOCK AREA, DUBLON: View supply receiving facility from pier, showing slip, foreground, and poorly con­

structed timber wharf, middleground, for smaller craft,

The 45, 65, and lOOkva generators were removed from their respec­tive base site buildings and Installed in caves in the adjacent hillside. A typ­ical underground installation is shown in Picture Nos. 172 and 173.

Two small sawmills were operated by the base personnel cutting 24" imported hard wood logs and local soft wood breadfruit trees.

The 300-ton marine railway, 36* wide, 250' long, built on a 1 to 15 slope of 41 thick concrete slabs, was never completed. (See Picture Nos. 174 and 176).

A floating drydock, 117 meters in length and 18*7 meters in breadth, lay inshore at the base and was reported to have been used for docking destroyers, submarine and small craft* The dock could be sunk 4*8 meters below normal dis­placement* (See Picture Nos* 177, 178, 179, and 180)*

4th Communications Unit Transmitting Station-The layout of this stacion is shown in Figure 24* All buildings were of frame construction* The two-story barracks were set on concrete piers* After US bombing began these facilities were salvaged and crude open barracks built for them in the adjacent wooded areas*

The two power plant buildings with concrete decks, 41 high sill walls and wooden superstructures were totally destroyed by US bombing* The Japanese had anticipated severe bombing attacks and had removed all machinery and transmitting equipment to a prepared underground site and so suffered little interruption to their signal communications.

The ruins of the former transmitting rooms showed evidence of hand rubbed finish on the Interior of the concrete walls as well as on the interior wood trim. Glass sash had been provided*

Three steel 45-meter masts set in concrete foundations supported the antennae.

The newly prepared underground site Included a power house, two transmitting caves and provided only the bare essentials. The entrance to one of the transmitting caves is shown in Picture No. 184.

The power house sheltering the 65 and 60kva generators was of heav­ily reinforced concrete construction with 18" walls, 36" roof slab, and concrete deck. The entire building was oovered with earth and sodded. No ventilation was provided and the air inside was hot and smelled of grease. The two cut-and-cover transmitting shelters, of reinforced concrete construction and of horseshoe cross section, were 601 long, 12* wide, 81 high and had walls 12" thick. A 12" X 12" combination ventilation duct and escape hatch made these units quite habitable.

70

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JAPANESE DEFENSES O N TRUK A T O L L , C A R O L I N E I S L A N D S . C I N C P A C - C I N C P O A BULLETIN 3 -46 , 15 M A R C H 1 9 4 6 . (

SINGLE MAST

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COOK"HOUSE

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SHELTER NO. I

TO BRANCH OFFICES

RADIO EQUIPMENT MOVED TO CAVE

OFFICERS I—I

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w QUARTER OFFICERS i 1 I SINGLE MAST I i

CIVIL RADIO STATION

L _ J • MAIN MAST GENERATOR

i I

RECEIVING ROOM BARRACKS FIGURE NO. 28

N02 i NO.3 _] COMMUNICATION. UNIT RECEIVING STAT

(DUBLON ISLAND)

HEADQUARTERS OFFICE NOTE: DASHED BUILDINGS DESTROYED

DRAWING NOT TO SCALE

SHELTER NO. 2

WORKER'S BARRACKS TO SEAPLANE_BASE

7,000 ton

OIL STORAGE TANKS WAREHOUSES

FIGURE NO. 27 BARRACKS

SUPPLY WAREHOUSE AREA WAREHOUSES (4th MUNITION DEPOT)

CD FACTORY 10 0 10 20 30 40 50 60 70 80

SCALE IN METERS

7 3

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BACILLUS RESEARCH ROOM!

WC O STORE­ROOM

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TUBERCULOS WARD WATER

OFFICER S AREA in

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FIGURE NO.29 a UJ CO UJ

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4TH NAVAL HOSPITAL GARAGE STORAGE

(DUBLON ISLAND)

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DUBLON FIGURE NO. 31

AIRFIELD NO.I(MOEN ISLAND) L Z T Z I GALLEY nmfm

200 400 600 800 BARRACKS OIL TANKS

ETEN

PROPOSED EXTENSION BOMB

STOREHOUSE OIL TANK

WELDING SHOP I I

DISPENSARY

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CONTROL TOWER

BOMB STORAGE PLANE

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PLANE REPAIR

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PROPELLER AERO­ AERO-GAUGE S H 0 P MACHINE REPAIR

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FIGURE N0.30 104TH AIR FORCE ARSENAL (NAVY)

DRAWING-NO SCALE

10 TON CRANE

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FIGURE N0.32 AIRFIELD N 0 . 2 A N D SEAPLANE BASE

2 0 —- - Z Z Z :

— — • ­ CONCRETE PAVING GRAVEL PAVING

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LEGEND SAME AS FIG.3I 200100 0 200 400 600

UNDERGROUND HANGER-I PLANE CAPACITY

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ALL DIMENSIONS IN METERS

75