Nachi (draft)

PREFACE

In mid-May 1944 the two largest carrier forces that ever fought were in their advance bases facing one another across several thousand miles of the Pacific. The bulk of Task Force 58, the American carrier force, was at Majuro in the Marshall Islands preparing for its role in the invasion of the Marianas. To the west at Tawi-tawi in the southwest Philippines much of First Mobile Force (Dai Ichi Kido Butai), the Japanese carrier force, was poised to meet the next American move.

Had one been able to visit both advanced bases they would have been struck by the broad similarities in the two collections of men of war. Leaving aside the differences in appearance that made the ships look “Japanese” or “American” the ships of both fleets bristled with heavy machine guns. In contrast with the pre-war appearance of ships of both navies masts were now topped with radar antennae and the other antenna of the new era of electronic naval air warfare. One striking difference was the presence of three hybrid cruiser seaplane carriers in the Japanese force. These three ships were a hint of an important difference in the way the two navies would fight the upcoming battle. It was as if the two navies were fighting in parallel universes.

In 1942 both navies had conducted extensive carrier operations and fought four carrier battles. Three were close fought actions and even at Midway, a decisive American victory, the thing was more closely fought than the final results might indicate. Each navy brought a wealth of battle lessons away from the carrier fighting and each sought to apply those lessons to the upcoming campaigns.

At the beginning of the war both navies had codified their tactics and doctrine in a series of publications. War games, both at sea and in table top maneuvers, which focused on the clash of battleships produced these documents. When war came the pace of operations and the radical changes brought on by the emergence of the carrier as the new capital ship in both navies meant that they were learning by doing in 1942. For many reasons there were no carrier battles in 1943. This respite allowed both navies to revamp their entire doctrine. Much of the NACHI find deals with that update of Japanese doctrine.

Foreword (The NACHI Affair)

She lay in a little over 100 feet of water five nautical miles southwest of Corregidor. Less than two weeks after the Leyte Gulf defeat aircraft of Task Group 38.2 found her and on November 5, 1944 sank her. When Manila Bay was finally secured in April 1945 submarine rescue ship USS CHANTICLEER was brought in to work the various wrecks

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in the Manila Bay area. NACHI was the crown jewel. The divers went to work on April 14. Almost immediately they were bringing up the secret orders of the Japanese Navy. By the time they were finished they had one of the largest single intelligence coups of the war. A portion of the recovered items consisting of Operations Orders, Doctrinal Orders and the like were translated and published in a twelve volume set which was given limited distribution.

Even a brief summary of the translated documents illustrates the magnitude of the find:

I. SHO GO OpOrds (Leyte Gulf OpOrds)II. NIGHT FORCE DOCTRINEIII. MOBILE FORCE DOCTRINEIV. NORTHEAST AREA FORCE DOCTRINE and SECOND BASE

AIRFORCE OPORDS, 1943-4V. SECOND DIVERSION ATTACK FORCE DOCTRINE 1944VI. OMINATO GUARD DISTRICT OPERATIONS ORDERS 1943-4VII. COMBINED FLEET DOCTRINE 1943 COMBATVIII. OPORDS 1941-4IX. DESTROYER DOCTRINE AND PROCEDUREX. CARDIV 4 DOCTRINE, CRUISER DOCTRINE, DIVERSION ATTACK

FORCE DOCTRINE, IDENTIFICATION OF FRIENDLY FORCESXI. NORTHERN FORCE ORDERS, COMMUNICATIONS LESSONS OF THE

BATTLE OF ATTUXII. SOUTHERN FORCE ORDERS

During most of the war NACHI served as fleet or division flagship so she was on the distribution list for most operational and doctrinal publications. She was assigned to Cruiser Division 5(5S) Second Fleet (2K) until July 1942 when she was transferred to 21S 5K. While with 2K she participated in the Battle of the Java Sea. Most of her career with 21S involved regional defense and convoy operations in the north Pacific. She ended her run as did many Japanese warships, in the Battle for Leyte Gulf and its aftermath.

This is not an operational history nor is it intended as a comprehensive treatment of Japanese Tactics and Doctrine. During the war the U. S. Navy captured many sensitive Japanese documents which were translated and given “need to know” distribution. This is not a treatment of that body of work, but a discrete look at the largest single collection.

Distribution of 40 copies of the translations to 15 addressees began almost immediately with the first installment going out on April 22.

The Dive

The general condition of the wreck created a number of problems. The main section of the hull lay at a 45 degree angle to starboard. The bow forward of the 8” guns was missing and the stern aft of #5 8” turret was severed and upside down. The wrecked

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condition of the hulk from the number of hits made work difficult. She had been down long enough for barnacles to attach and the remains of 800 dead crew were everywhere one would expect in a fighting warship. Underwater cutting torches had to be used to get into many compartments. In spite of all of these difficulties the divers were rewarded with, “(s)everal articles of historical value . . . including a vice admiral’s flag (now held by the USNA). Documents containing Japanese strategy, tactics, amphibious operation instructions and ship’s logs were salvaged which will contribute greatly to the writing of a history of World War II.”

As items were brought up steps were taken to clean and preserve them. The documents were then flown to Hollandia. By April 22 the first of twelve volumes was ready for distribution.

Salvage operations continued until August 26, 1945. By that time, in addition to the documents mentioned, the divers also brought up a shipboard radar with its instruction manual along with underwater sound equipment. Navigation documents and charts were also brought up.

1 Task Force Ultrasecret Operation Order 76 and 77; Order 76 and Serials 108, 1003 and 1084 Sho-Go

The first set of documents translated and distributed related to the Battle for Leyte Gulf. Portions of these orders have been published elsewhere, though the various cruising and approach orders have not, nor has the outline of movements.

Documents related to Sho-Go, the Operation that led to the Battle for Leyte Gulf Task Force Ultra Secret Operations Orders 76 and 77; Order 76 and Serials 108, 1003 1084(1944).

1. Task Force Ultrasecret Operation Order 76 and 77, 10 August 1944: Outline of Operations of the Task Force in SHO Operations.

a. General Policy for operations b. Concrete operational policy: Outline of SHO 1, 2, 3 and 4 Operations. c. Allocation of Forces: Lists commanding officers, strength and main duties in Allocations of Forces 1 to 4. d. Combat methods e. Air Combat: Disposition for attack, outline for air combat. f. Outline of operations: Various unit operations which the situation may rise to before the main engagement, outline of battle, anchorage. g. Supply h. Communications (ship and airplane)

i. Order of cruising under alert (KEIKAIKOKO), General rules, sketches showing various orders.j. Order of approach (two sketches)

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k. Separate charts, Outline of movements for SHO 1, 2, and 4 Operations and for Bonin Island Area Operations.

2. Task Force Ultrasecret Serial 108 17 Aug. 1944 (Errata for #76)

3. Task Force UltraSecret Serial 1003, 10 Aug 1944, Statement of Chief of Staff on Task Force operations in Sho Operations.

4. Task Force Ultrasecret Serial 1003, 10 Aug 1944-Plan for table topManeuvers 6. Daily schedule and place, principal items for training and

study (Task Force operation in the Sho Operations), organization of supervisory personnel and maneuver personnel, etc.

5. Task Force Ultrasecret Operation Order 77 “Plan for carrying out base air defense while in training on the mainland.

6. Task Force Ultrasecret Serial 1004 10 Sept. 44 Main points in training task force Hikokitai (air groups). Employment of aircraft, maintenance, communications.

************************************************************************Note:

Since most of the preliminary items (glossaries of Japanese terminology, English-Japanese translations of recurring terms with KANJI [Chinese characters used in Japanese writing] and ROMAJI [Roman letters used to spell Japanese words phonetically] renderings of the Japanese words that are not subject to translation [proper names, places, ship names and in rare situations, technical terms that defied translation or were of uncertain meaning at the time], tactical terms and IJN plotting symbols) are repeated in each volume this is a good time to set them out in some detail and not repeat them in each section..

Editor’s Notes1. Special terms have been given generally uniform translations based on the

following references:

a. Glossary of Japanese General terms, 11 Nov. 1944 (ATIS Publication 3, Advance Copy 5).

b. Glossary of Japanese Radar and Radio Terms, 12 Dec. 1944 (ATIS Publication 3, Advance Copy 4)

c. Glossary of Japanese Antiaircraft Terms, 29 Jun. (ATIS Publication 3, Advance Copy 3)

d. Translation Aids: General Terms, 27 Jun 1944 (JICPOA Glossary)

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e. Japanese Naval Air Organization, 22 Jan. 1945 (CINCPAC-CINCPOA Bulletin 16-45)

2. Recurrent terms not found in the above named references have been given the following standardized translations:

a.English-Japanese (Kanji omitted here)

Abbreviated Code: RyakugoAir Control Sector: Koku Kansei KuikiAir Task Force Operation: Koku KidosenBase Scouting Sector: Kichi Sakuteki KennaiCoordinated Action: Kyodo DosaDispatch: DenDoctrine: SakusenElectric Ranging: DensokuGuide Unit: KijuntaiHit and Run Raids: Tansetsunaru Kishu KogekiInverted V Formation: Kakutoku JinkeiJoint Army Navy Agreement: RikukaigunChuo KyoteiKurile Islands Base: ChikonLoading Unit: SenyotaiOrder of Approach: Setteki JoretsuOperational Priority: Sakusen Kiukyushin (see note c below)Priority: Kankyu ShubetsuPriority: Shikyushin (see note c below)Radar Decoy Unit: Dentai YodotaiRadar Intercept Device: Dempa TanchikiRendezvous: Taiki HakuchiRoutine: Futsushin: (see note c below)Senior Officer of the Watch: ShokaishoShips and Stations: KanshoSkip Bombing Unit: Nancho BakugekitaiTable Top Maneuvers: Zujo Enshu

b. The Japanese English section has been omitted.

c. Communications Priorities: (Japanese: Translation: Approximate USN Equivalent)Sakusen Kinkyushin: Operational Urgent: UrgentKinkyushin: Urgent: Operational PriorityShikyushin: Priority: PriorityFutsushin: Routine: Routine

3. Because the following terms cannot be translated with precise uniformity when designating types of Japanese Navy air formations they are given in ROMAJI, a procedure recommended by CINCPAC-CINCPOA Bulletin 16-45:

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BUNTAI, CHUTAI, DAITAI, HENTAI, HIKOBU, HIKUKITAI, HIKOTAI, KOKUTAI, KUTAI, SHOTAI, SHUDAN, TAI

4. Abbreviations have been translated uniformly in accordance with the following references:

a. Japanese Roman Letter Abbreviations, 13 Jan 45 (CINCPAC-CINCPOA Bulletin 2-45)

b. Japanese Map Symbols and Abbreviations, 15 Jul 44 (JICPOA Bulletin 111-44)c. Japanese Military Conventional Signs and Abbreviations, 4 Mar 43 (ATIS

Publication 1); Advanced Copy 1 of Revised Chapter 2, same publication, 10 Oct 44

In addition, the following abbreviations and symbols have been translated as indicated:

Cdg: Desdiv Group (This abbreviation, and the term KUCHIKU RENTAI which it represents, indicates a unit smaller than a squadron and larger than a division.)D: Section (SHOTAI)KdMB: Main Body of a Task ForceKdF; Mobile FleetLCS: Light CrudivSEN B: Kurile Islands Defense Force (SHISHIMA BOBI BUTAI)Sig: Support Unit21S: Crudiv 21K22S: Crudiv 22

There follow two flags: one with a ball atop the mast indicating CinC Combined Fleet; the other without the ball indicating CinC Fleet or OTC)

The abbreviations have not been reproduced except (a) in tables where the original document gives both the abbreviation and the long form and (b) in charts. Keys of abbreviations and symbols appear on each chart or on the first chart of each series.

5. In addition to using both Chinese and Arabic numerals, KANA syllables (usually in the I-RO-HA sequence), and letters from the Roman alphabet, Japanese Texts also frequently enumerate or classify a series through the use of 10 Chinese characters, originally calendrical in significance, which have the following ordinal value: KO=1; OTSU-2; HEI=3; TEI=4; BO=5; KI=6; KO=7; SHIN=8; JIN=9; KI=10

Throughout the translation of these documents the first four methods have been translated by the suitable use of Roman and Arabic numerals, and letters of the English alphabet. Where the “calendrical” characters occur, however, they have simply been transliterated (as KO, OTSU, etc) since their only meaning is to express a different order or series from those which may be lettered or numbered.

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2. Night Operations Force Doctrine

This volume was translated and distributed in May 1945. It consists of two parts: Second Fleet Night Operations Doctrine and Fifth Fleet Night Operations doctrine.

If you are familiar with Peattie and Evans’ treatment of their night operations doctrine of the late 1930s you might be struck by how little has changed. The drawing in the 1944 doctrine has changed to fit the ships that were available in 1944. The idea of surrounding the American force is still central to their tactical scheme.

General: Night combat doctrine is governed by the basic principal that all units will search diligently for the enemy, will be tracked doggedly once discovered. Every attempt will be made to outflank enemy formations and new units if isolated from older units will be attacked first. Enemy carriers, battleships and cruisers are the prime targets in that order, with transports given top priority in interception operations.

Open Seas: Planned surprise attack is the basis for success in night operations, consequently all available techniques for discovering the enemy will be utilized. Battleships will use their superior firepower to break through enemy screens to support cruisers and destroyers in their attacks. Cruisers will support battleships in covering torpedo attacks, particularly with Type 4 Projectiles (O Hassa) and star shell illumination. Destroyers will rush in and destroy the enemy main body with torpedo attacks. Generally carriers will avoid night combat.

Identification of Friendly Forces information will always be at the ready in night action.

Because of the dangers of night operations knowledge of the enemy and one’s own forces is essential. The following reports are the standard required:

Type Report Items of Report Items to NoteEnemy Discovered Strength, position, course,

Speed, disposition, positionrelative to own forces, actiontaken by own forces.

The discovery of the enemy will be quickly reported and then the foregoing items will be reported in succession

Contact lost Same as aboveWhen there is a change in the situation; When help from friendly forces is requested; When the occasion requires.

Enemy situation, course, speed, location, strength, disposition, and changes in the foregoing.

Even when there is no extensive change in the enemy situation it is permissible to report to that effect.

When dispositions have been made. When the

Station of own unit, including location and range and bearing

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situation requires. of the enemy.When preparation for the attack have been completed.

Organization of preparation for attack (including station of own unit when necessary).

When proceeding to attack

Proceeding to the attack when necessary arrangements for attack, attack course, direction of torpedo action and whether on same or opposite course

Moment when attack is completed

Attack Completed.

After attack completed Combat situation: Results of the attack, losses, station, movements of own unit.

The types of Night Operations are as follows:

Type Outline of CombatNight Op. A (Ko)

All forces combine and carry out night operations against a single objective.

Night Op. B (Otsu)

If the enemy is dispersed, generally our entire force will be used first to destroy his newest and most powerful units and then will engage his other units.

Night Op. C (Hei)

When the enemy is dispersed, our force will also separate and carry out night operations.

Night Op. D (Tei)

When the enemy is making a disorganized retreat he will be pursued and annihilated, using the outline of daylight pursuit action as a guide. One element will be assigned to destroy damaged enemy ships.

Night Op. E (Bo)

When there is an enemy screening force, it will be bypassed unobserved and night operations will be carried out against the enemy main body.

Scouting: Cruisers are the principal surface scouting vessel though destroyers and even battleships can be used if there are insufficient units to cover the assigned scout sectors. Cruisers will be accompanied by destroyers if enemy action is probable. Scouting units will avoid engagement, tracking, reporting and assembling friendly forces. In the event of counterattack by the enemy then the tracking unit may fight and then resume tracking. Cruiser divisions will not normally be reduced below a section (two ships) for scouting duties. Signals for Scouting Dispositions will normally include basic course, speed and disposition chosen.

Tracking: Cruisers are the principal tracking surface warships. The basic method for tracking is as follows:Enemy followed from station close to limit of rearward vision field (effective radar range) from astern or on his quarter.Engagement with the enemy should be avoided if at all possible.

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If attacked maneuver radically and make smoke and in proper circumstances counterattack.If enemy is lost in tracking resume scouting.

Attack: General; Disposition should be completed outside enemy vision based on reports of tracking units (aircraft and cruisers). Use of Long range torpedo firing (O Hassa) and progress of advance of destroyer squadrons should be reported. Generally the attack order should be given by the commander though all attack opportunities should be seized without awaiting signals. Fierce action at close quarters is recommended and units are advised to clear the battle area after they have delivered their blows returning only when the opportunity presents itself.

Night Action in Narrow Waters: Governed by the same rules of engagement as in Diversion Attack Force Doctrine.

Scouting Dispositions

Night Operations Dispositions

Type Disposition (Tracing of original document)

Station of Each Unit

Outline of Combat

Night Operations Disposition 1

Cruiser divisions will concentrate their strength as much as possible. When they have proceeded close to the desired disposition point of the destroyer squadron located near the limit of visibility (beyond effective radar range) they will fire long range torpedos(O Hassa). Then, closing in (they must be careful not to come too soon within the enemy’s effective radar controlled firing range) they will carry out a full scale attack.

Battleships (batdiv) will take up stations on the disengaged side of the cruiser divisions, or, at some other suitable stations. Coordinating their attack with that of the cruiser divisions they will fire upon the enemy with the aid of searchlight illumination and star shell fire of their own and other ships.

The destroyer squadron will proceed

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with the utmost secrecy to a point off the enemy’s bow and will endeavor to carry out a surprise attack, taking advantage of the effects of the O Hassa by the cruiser division and the effect of the bombardment by the battleships and cruiser division. Generally the units stationed to the rear will attack in concert with the units stationed to the fore.

In accordance with orders, the enemy will be destroyed at one blow by an all out attack.

When the full scale attack begins tracking planes will endeavor to drop flares continuously over the enemy and will promptly report enemy movements.

Night Operations Disposition 2Night Operations Disposition 3

In Organization 2(11)(13)-1 Night Operations Unit(12)(14) 2 Night Operations Unit

In Organization 4 (11)(13) 1 Night Operations Unit(12)(14) 2 Night Operations Unit(21) or (22) Support Unit

In Organization 6 (11)(13) 1

The greater part of the force will attempt to encircle the enemy from both sides. One part will track to the rear or off the quarter.

In accordance with orders, the units on both sides will carry out a simultaneous attack. If a good opportunity presents, the tracking unit will attack with those units.

The outline of combat for each unit will conform to Night Operations Disposition 1 & 2.

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Night Operations Unit (12)(14) 2 Night Operations Unit(21) or (22) Support Unit(0) 3 Night Operations Unit

Night Operations Disposition 4

Here are some USN hypothetical formations that might have encountered the Japanese Night Operations Force as well as it daylight version; Diversion Attack Force:

For simplicity battleship formations that were either contemplated or actually organized are used:

Task Group 58.7 (June 1944)WASHINGTON, NORTH CAROLINA, IOWA, NEW JERSEY, SOUTH DAKOTA, ALABAMA, INDIANA, WICHITA, MINNEAPOLIS, NEW ORLEANS, SAN FRANCISCO, 13 DDs

Task Force 34 (October 1944)IOWA, NEW JERSEY, MASSACHUSETTS, WASHINGTON, SOUTH DAKOTA, ALABAMA, VICKSBURG, HOUSTON, MIAMI BILOXI, CHESTER, PENSACOLA, SALT LAKE CITY, 18 DDs

Task Group 34.5 (October 1944)IOWA, NEW JERSEY, VICKSBURG, HOUSTON, MIAMI, BILOXI, VINCENNES, 5 DDs

Old Battleship Force at Surigao:MISSISSIPPI, MARYLAND, WEST VIRGINIA, TENNESSEE, CALIFORNIA, PENNSYLVANIA, LOUISVILLE, PORTLAND, MINNEAPOLI, PHOENIX, BOISE, HMAS SHROPSHIRE DENVER, COLUMBIA, 28 DDs

Admiral Oldendorf’s detachment sent north to meet Admiral Kurita’s Force:TENNESSEE, CALIFORNIA, PENNSYLVANIA, SHROPSHIRE, LOUISVILLE, PORTLAND, INDIANAPOLIS, 20 DDs.

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By the time Kurita had reached the open water outside San Bernadino Strait his force was so reduced that would not have had the ships to man all the stations envisioned in the plan.

3. Mobile Fleet Doctrine

The third item translated was Mobile Fleet Doctrine. In March 1944 there was a major reorganization of the combat arm of the Japanese Navy. Almost all ships, destroyer size and larger, not assigned to area fleets, were put under one administrative command, First Mobile Fleet (Dai Ichi Kido Kantai). On March 25 Admiral Ozawa issued First Mobile Fleet Doctrine. It would serve as the doctrine for the upcoming fights in 1944 and as such will be given extended treatment. Most of the following is a synopsis of what is in the original text. Portions that are quotes are noted.

MOBILE FLEET DOCTRINE

I. General Rules

II. Combat

A. Combat Policy: “Combat by First Mobile Fleet is based on the fundamental policy of complete dependence on air attack. The aim is to take the initiative bringing the full strength of the air forces to bear through close cooperation of all forces, first to

destroy the enemy aircraft carriers; then employ the full strength of the fleet to pursue and annihilate the remaining enemy forces.”

B. Standard Distribution of Fighting Forces (in a separate annex not recovered)

C. Classification of Combat MethodsCombat Method 1: Mobile operations would be carried out using disposition in depth by the main unit and the vanguard.Combat Method 2: Envelopment dispositions were to be used. There were two versions. In the first the force would divide into two groups, and in the second (referred to as Method Ko) the force would divide into three groups.Combat Method 3: The force was to mass in one group and carry out mobile operations. Combat Method 4: The majority of the air groups (Hikokitai) will operate from land bases and the remainder of the strength will remain afloat. In a second version (Method Otsu) the majority would remain on the carriers but a part would operate from land bases. In either case the surface forces would be given special tactical orders.Combat Method 5: Diversionary movements were to be carried out with a designated force to decoy the enemy carrier group. Advantage would be taken of the fact the enemy carriers were limited by their movements in response to the decoy operations.

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Combat Method 6: A shift to the decisive battle with surface combat forces and carriers in a supporting role. Combat Method 7: The enemy transport convoys or invasion force would be attacked. D. Attack Dispositions

E. Air Combat

1. Surface Mobile Operations

a. General Policy for Air Combatb. Dawn Air Combat: Dawn air attack was preferred. Contact would be maintained

during the night. Mobile Force was to close the range and in the pre dawn hours the Zero fighter bombers would attempt to disable the enemy carriers with the main attack coming at dawn. Every effort was to be made to conceal the approach of Mobile Force with scouting conducted in waves. The pursuit of a defeated enemy force was to be relentless. Note: at this time the Zero fighter bomber force was referred to as “Tokubetsu Kogeki Tai” (i.e. “Special Attack Force”) a tactical designation later used by the Kamikazes. The use of this term at this time should not be confused with its later use.

c. Day Air Combat: Day air combat emphasized stand off tactics taking advantage of the superior range of Japanese aircraft with the range being closed only after the enemy carriers had been disabled or destroyed.

d. Dusk Air Combat: Dusk air attacks were discouraged unless day air combat had not completed the destruction of enemy forces or the tactical situation outweighed the disadvantages of such attacks. In the event of dusk air combat the commander of Mobile Force might separate the carriers from surface units and dispatch the latter to “increase the results” of the dusk air attacks. The carriers were to avoid the battle area and at the same time remain close enough to exploit night or dawn air combat situations. Preferably the carriers were to operate to windward of the battle area.

e. Night Air Combat: Night air combat was not recommended for carrier air groups because of the problems involved in night recovery. If, however, moonlight, starlight or general conditions permitted night air attack with the same techniques used by shore based air it could be used as a continuation of the day or dusk attacks because of the value of the surprise element.

2. Air Combat Utilizing Land Bases

F. Surface EngagementsG. Invasion Operations

III. Procedure

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A. Order of Cruising Under Alert (Keikaikoko): The same basic rules applied to cruising under alert for carriers that applied to surface ships, but no special formations were included in Mobile Fleet Doctrine.

B. Order of ApproachC. DeploymentD. MovementsE. Air CombatF. Gunnery EngagementsG. Picking Up Returning AirplanesH. Smoke ScreensI. Use of Radar Ranging Equipment

In August a Signal Appendix was issued (whether this replaced a previous appendix or not is unclear from the text, though there is no indication it did).

Appendix

I Order of Cruising Under Alert (Keikaikoko)II. Circular Formations

Circular Formations and special signals are determined as follows:

Signal Text Formation NotesJin ZA Take

CircularFormation A

Copied from an exact tracing of original document

Jin ZB Take

CircularFormation B

Jin ZC Take CircularFormation C

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Jin ZD Take CircularFormation D

Jin ZE Take Circular Formation E

Jin ZF Take CircularFormation F

Jin ZG Take Circular Formation G

Jin ZH

Take CircularFormation H

Jin ZI Take CircularFormation I

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Jin ZK Take Circular Formation K

Jin ZL Take CircularFormation L

Jin ZM Take CircularFormation M

Jin ZN Take CircularFormation N

Jin ZO Take CircularFormation O

Jin ZP Take

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CircularFormation P

Jin ZQ Take CircularFormation Q

Jin ZR Take Circular Formation R

Jin ZS Take CircularFormation S

III. Antisubmarine Formations

Antisubmarine Formations Antisubmarine formations and special signals for those formations used when a direct escort is assigned to a carrier division (battleship division) are established as follows:

Signal Text of Message Antisubmarine Formation

Notes

Jin 2A Employ Antisubmarine Method A, sections in Column in numerical (reverse) order.

Copied from tracing of original document

1. Order when omittingThe direct escort ship(7)(0)2. Group 1, Section 1

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(Jin7A)

(Employ AntisubmarineMethod A, sections inLine in numerical (reverse) order.

(0)(1)(3)(5)(Section 1 [0][1][2][3]Group 2, Section 2(2)(4)(6)(7)(Section 2 [4][5][6][7](Note) The figures inBrackets apply when the signal Jin 7A is given. The same appliesbelow.

Jin 2B

(Jin7B)

Employ Antisubmarine Method A, sections in Column in numerical (reverse) order.

(Employ AntisubmarineMethod B, sections in lineIn numerical (reverse)order)

1. Order when omittingThe direct escort ship7 (0)

2. Group 1.Section 1 (0)(1)(3)(5)

[Section 1 (0)(1)(2)(3)Group 2, Section 2 (2)(4)(6)(7)[Section 2 (4)(5)(6)(7) The figures in brackets apply when the signal Jin 7A is given

Jin 2C

(Jin7C)

Employ Antisubmarine Method C in numerical (reverse)order. (Employ Antisubmarine Method C, sections in line in numerical order.

When the direct escort is missing omit (0)

Jin 8A Employ Antisubmarine Method A using triangular Formation, Odd numbers on the right (left)

1. When the direct escort is missing omit (0)

2. Group 1 (I)(0)(1)(3) [(I)(0)(2)(4)Group 2 (II)(2)(4)[(II)(1)

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(3)

Jin 8B Employ Antisubmarine Method B using triangular formation, odd numbers On the right (left)

When the direct escort is missing omit (0)

Jin 8C Employ Antisubmarine Method C using triangular formation, odd numbers on the right (left)

1. When the direct escort is missing omit (0)

2. Group 1. (I)(0)(1)Group 2 (II)(2) [(I)(2) [(II)(1)Group 3 (III) (3)(4)

Jin 6A Employ Antisubmarine Method A, single line in numerical (reverse) order

1. When the direct escort is missing, omit (0). In this case (7) will take station between 1.5km to the rear of (I) and (II)

2. Group 1 (I)(3)(5)(7) [(I)(2)(4)(6)(8)]Group 2 (II)(2)(4)(6)(8) [(II)(1)(3)(5)(7)

Jin 6B Employ Antisubmarine Method B, single line in numerical (reverse) order

1. The order when the direct escort is missing is (5)(4). But when (4) is missing the angle of station of (2) is 80degrees.

2. Group 1 (I)(0)(1)(3)Group 2 (II)(2)(4)(6) [(II)(1)(3)(5)]

Jin 0A Employ Antisubmarine Method A, single column in numerical (reverse) order

Group 1 (I)(0)(1)(2)(3) [(I)(4)(5)(6)(7)Group 2 (II)(4)(5)(6)(7) [(II) (0)(1)(2)(3)

Jin 0B Employ Antisubmarine 1. When the direct escort

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Method B single column in numerical (reverse) order

is missing omit (7)2. Group 1 (I)(1)(2)(3)(4)

[(I)(5)(6)(7)]Group 2 (II) (5)(6)(7) [(II) (1)(2)(3)(4)

Jin 0C Employ Antisubmarine Method C single column in numerical (reverse) order

1. When the direct escort ship is missing the station of (1) and (2)will be 80 degrees

2. Group 1 (I)(0)(1)(2) [(I)(3)(4)]Group 2 (II)(3)(4) [(II)(0)(1)(2)

IV. Order of ApproachV. Standard Landing and Take off Procedure

The formation and special signals for take-off and landing of airplanes of a carrier division will be in accordance with the following:

Signal Text Formation

Un Ko 1 Assume Take-Off andLanding Formation1

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Un Ko 2 Assume Take-Off andLanding Formation 2

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Un Ko 3 Assume Take-Off and Landing Formation 3

Un Ko 4 Assume Take-Off andLanding Formation 4

Un Ko 5 Assume Take-Off andLanding Formation 5

Un Ko 6 Assume Take-Off andLanding Formation 6

VI. Various Regulations for taking on AirplanesVII. Standard Procedure for Avoiding Torpedo and Bombing AttacksVIII. Standard Ship-borne Radar Search ProcedureIX. Standard Formations for SupplyingX. Signal Communications SystemsXI. Prearranged Signals (Signal Appendix)

4. Northeast Area Force Doctrine and Second Base Air Force OpOrds 1943-1944

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I do not have this volume

5. Second Diversion Attack Force Doctrine

Vol 5 Diversion Attack Force Ultrasecret Operations Orders and Orders 1944

Second Diversion Attack Force Ultra Secret Operation Orders OperationOrders and Orders 1944I. Standing order 10 Organization of Fifth Fleet (2YB) inSHO OperationII. Plan of Operations (SHO), distribution of forces, outlineof operation, supply and charts showing movement plans fpr SHO 1, 2 & 4III. Plan for Supply SHOIV. Support Unit (Betsudo) Regulations for SHOV. Plan for SHO Table Top ManeuversVI. Identification of Friendly Forces in SHOVII. ASW screen by 954 & 955 Kokutai for 1YB and 2YB in SHOVIII. Sortie order for SHO

6. Ominato Guard district Operations Orders 1943-4

I do not have this volume

7. Combined Fleet Doctrine: 1943 Combat

General Principles: The basic evolution unit for Japanese battleships (and heavy cruisers) was the squadron or division (Sentai) designated by the Arabic numeral-Roman letter “S” combination which corresponded to its squadron number thus; 1S=Battleship Division 1. The first three numbers were reserved for battleships, the balance to heavy cruisers. Standard distance for battleships was 800 meters. Speed signals are treated in the signal appendix.

Acceleration for battleships in minutes: seconds was as follows:Time required to accelerate from one speed to the next. Total elapsed time Standard speed: 12 knots to 14 knots: 1:00 1:00

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Full speed: 14-16 knots 1:00 2:00Battle Speed 1: 16-18 knots 2:30 4:30 Battle Speed 2: 18-20 knots 2:30 7:00Battle Speed 3: 20-22 knots 3:00 10:00Battle Speed 4: 22-24 knots 3:00 13:00Battle Speed 5: 24-26 knots 4:30 17:30

The Interception Zone Combat, Base Air Force Combat and Air Combat are omitted as they are either not discussed anywhere or are treated elsewhere.

Surface Action: In the approach phase of a battle the Japanese battleship force was to steam in an ALERT CRUISING DISPOSITION or APPROACH DISPOSITION similar to those in the sections on Diversionary Attack or Night Operations (see Chapters 2, 5 and 10) selected by the officer in tactical command or one set out in the operations order for a specific operation.

When contact is obtained the vanguard was to proceed immediately in the direction of the enemy and maneuver to become the leading or rear unit depending on the overall tactical situation.

It was suggested the officer in tactical command dispatch preliminary orders for deployment when the main bodies were about 50 km apart, about 15 minutes before opening gunfire. The guide unit would normally be 1S (YAMATO, MUSASHI)* and the direction of deployment would be ordered at this time. The APPROACH DISPOSITION would be line abreast of lines of divisions at approximate right angles to the direction of the enemy, with the order of battle being a column formation. Prior to deployment the interval between divisions will be maintained at 4 km. unless otherwise signaled.

DAY ACTION: Day actions by surface forces normally were actions on the same course with a concentration on the enemy van. At a suitable time deployment was to be completed. The surface forces would proceed into the path of the enemy force and take up a position which would permit them to overwhelm the enemy van. All forces would cooperate in cornering the enemy main force, then the whole force would concentrate and destroy the enemy. If the enemy deployed for an action on opposite course during the fight, an action on opposite course normally would be carried out.

There were three basic methods for conducting day actions on the same course:

Day Action KO (A): After the battleship divisions had begun the fight, at the first opening the entire force would carry out a strike.

Day Action OTSU (B): When visibility was very good, for awhile the battleship division would fire at long range with the angle of elevation of the main batteries at about maximum. The light forces would maneuver out of effective range of the enemy main batteries. Guns of large caliber and torpedo attacks by the cruiser divisions would be used to create an opening. Then the entire force would make its strike.

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Day Action HEI (C): Local superiority would be obtained by drawing up the entire force in a compact formation. One flank of the enemy main force would then be attacked.

Actions KO and OTSU were qualified as follows:

Method 1: The leading unit would move out. Later it would return. At that time deployment would be made.

Method 2: The whole force would be deployed as a unit. Unless otherwise ordered this method would be used.

In effect there were five formats: A1, A2, B1, B2, & C. These would be indicated by appropriate signals.

Employment of vanguard and 3S in Methods KO and OTSU: Method 1: The vanguard would proceed in direction of the enemy to obtain information of the situation. When ordered to deploy 3S (KONGO, HARUNA) take station 8 km obliquely to the rear of 1S (YAMATO, MUSASHI)*. 3S would maneuver so it can begin gun action against enemy main body simultaneous with 1S. Other leading units (heavy cruisers) would endeavor to deliver effective torpedo attacks against enemy main body simultaneous with 1S opening fire, reporting the time of firing and running time to Commander Main Body (1S), maneuvering to take station in the order of battle after firing their torpedoes. Method 2: Same as Method 1 except 3S wouldn’t move out so far.

1S would concentrate fire on the enemy van, signaling the opening of gunfire. Smoke would be used to attempt to divide the enemy. Detached enemy units would be taken under fire before the main gun action opens.

Van and rear guard light forces would, under their commanders, attack the enemy with guns and torpedoes as the opportunity presented itself. In the strike or mop-up phase the entire force would close the enemy attacking fiercely. Cruisers will open the way for destroyers and both cruisers and destroyers will deliver repeated torpedo attacks. Destroyers will attack the enemy main force and guard against possible reversal of course by the enemy main body.

Actions on opposite course were as follows:

Method KO (A): Using the greater part of the light forces an advance would be made into the path of the enemy force, then an attack would be delivered.

Method OTSU (B): The dispositions of the time would be used and an engagement while circling on opposite course would be carried out. Unless otherwise ordered, this method would be used.

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Dusk Action: There were two types of Dusk Action. Dusk Action KO (A) was based on Day Action KO. A single decisive action would be fought. This was the preferred method. In Dusk Action OTSU the force was to await night fall with the object of fighting a night action. Then all out action was to be joined. In addition to application of Day Action instructions every attempt was to be made to silhouette the enemy and take advantage of any meteorological phenomena. In Dusk Action OTSU the force will remain concentrated to avoid defeat in detail.

Night Action: There were five types of Night Action. In Night Action KO the entire force acting as a unit would carry out a night against a single target. Night Action OTSU would apply against a divided enemy force. The entire strength would be used to attack and destroy the nearest and most powerful enemy force. Then the rest of the enemy would be dealt with. In Night Action HEI own forces were to be divided to carry out night action against a divided enemy. In Night Action TEI the routed enemy would be pursued and destroyed as in the outline of day pursuit day action. One element would be assigned to deal with damaged enemy ships. In Night Action BO the enemy screen would be avoided and a night action carried out against the enemy main body. The fast battleships of 3S would be the only battleships to actively participate in night fighting, cruisers and destroyers being better adapted to night fighting. The ships of 3S were to be active participants in night actions and were assigned responsibility of cover and advance in Night Operations Force actions.

8. Combined Fleet Operations Orders, Orders and Serials 1941-4

As indicated by its title this item contains numerous (43 in all) operations orders and the like, many of which have been published elsewhere. All are listed. A synopsis is sufficient for most though a few are set out in part or in full.

1941-2:1. Operation Order #1. Combined Fleet Operations in case of war with U.S., Britain

and the Netherlands. Combined Fleet First and Second Phase Operations in case of war with the United States, Britain and the Netherlands, with measures for protection and destruction of sea traffic, mine warfare, communications, supply, etc; and in case of subsequent outbreak of war with Russia; with detailed tabulation of allocation of forces. This order is outlined in “Campaigns of the Pacific War” at pp. 47-48.

2. Operation Order #2. Orders “First Preparations for War” dated 8 December 1941.3. Operation Order #7. Additional procedure against enemy and neutral shipping4. Dispatch Order 21 removing limitations in OpOrd 7 regarding submarine and

aircraft attacks on shipping, excepting Russian shipping.5. Operations Order #4. Movement of forces for AL and MI Operations, standard air

patrols, codes, etc.

1943:6. Order #3 regarding pencil notes in signal books.

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7. Combined Fleet Memorandum 13. This order is of particular interest as it sets out the parameters for updating of doctrine in light of battle experience to date. It also establishes Second and Third Fleets as the primary sources for doctrinal statements for the combatant forces of the navy.

The Model for Change: Combined Fleet Memorandum 13 on Ultra secret Operations Orders, 15 August 1943.

In August 1943 Combined Fleet issued a memorandum to all squadrons, flotilla and division headquarters and to all base headquarters “to indicate the basic future policy of Combined Fleet operations and to attempt to unify concepts regarding the art of war in this period of transition when rules of naval warfare and COMBINED FLEET DOCTRINE are being re-examined.”

On December 5, 1943 COMBINED FLEET DOCTRINE: BOOK ONE (COMBAT) became the first document issued pursuant to this memorandum. It was followed by Second Fleet’s issuance of a series of doctrinal publications: DESTROYER SQUADRON DOCTRINE (12-18-43); DESTROYER SQUADRON PROCEDURE (12-18-43); NIGHT OPERATIONS FORCE DOCTRINE (1-1-44); DIVERSION ATTACK FORCE DOCTRINE (1-1-44) and CRUISER DIVISION DOCTRINE (1-22-44). All of these came from Admiral Kurita’s staff. Third Fleet, the carrier force was a bit slower issuing FIRST MOBILE FLEET DOCTRINE (3-28-44). The latter document was issued by Admiral Ozawa who now commanded the carrier force as well as FIRST MOBILE FLEET (DAI ICHI KIDO KANTAI) an umbrella organization which combined Second Fleet (the battleships and cruisers with their attached destroyer squadron) and Third Fleet (the carrier force with its attached destroyer squadron). The opening sentence of this new doctrine states the reason for this consolidation of the major combatant forces of the navy, “Combat by FIRST MOBILE FLEET is based upon the fundamental policy of complete dependence on air attack.”

Since it bears on so much of the NACHI find Memorandum 13 warrants repeating in full.

I. EXPLANATION OF THE OUTLINE OF COMBINED FLEET OPERATIONS

This memorandum has been issued to indicate the basic future policy of Combined Fleet Operations and to attempt to unify concepts regarding the art of war in this period of transition when rules of naval warfare and COMBINED FLEET DOCTRINE are being re-examined.

II. EXPLANATION OF THE BASIC ORGANIZATION OF VARIOUS FORCES OF THE COMBINED FLEET

A. Object in Promulgating These Orders

From the outset of the war to the present, operations for the most part have been based on pre-arranged plans. Since commanding officers and subordinates trained in the Combined

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Fleet before the war have conducted most of the action of the fleet, no matter what changes in the fleet have taken place, in general, operations have not been impaired. In the future, however, such will not necessarily be the case. The number of commanding officers and other personnel who are taking up duties and participating in organizations for the first time is increasing, and there will be unusual changes in the grouping of forces. Doctrine, combat regulations (SENSOKU), standard procedure (YOMU JUNSOKU), etc, suitable for each type of tactical unit will be established, therefore concepts regarding the art of war will be unified. Training will be given whenever the opportunity presents. Otherwise there is little hope that the fighting strength of the Combined Fleet can be maintained or improved.

At the present time the OUTLINE FOR COMBINED FLEET OPERATIONS not only established the basis for carrying out Combined Fleet operations, but also fixes the pattern for the basic organization of the forces. In addition, all commanding officers and staff officers will quickly establish doctrine and other matters required for combat.i

Training in these matters will be strictly enforced. It is anticipated that all these efforts will replenish and increase the fighting power of the Combined Fleet. These orders are promulgated to this end.

B. Significance of Basic Organization

1. Although the division of forces is ordinarily determined anew for each operation, it is advisable to point out in training pertinent division of forces selected from the entire range of operations. Hence, divisions of forces will be shown here as basic organizations for the various forces and will be set up alongside those determined for particular operations.

2. In issuing orders, particularly at important times care will be taken not to mix the two types, as indicated below:Basic Orders: Basic Organization, First Mobile Force Commander; Basic Organization, Night Operations Force CommanderRoutine Operations Orders: Previous examples will be relied on.

C. Classification of Doctrine of the Various ForcesBecause there can be two types of doctrine for individual forces (doctrine for each force in Combined Fleet operations and doctrine for individual forces operating as detached units), when necessary the two types will be set forth separately. However, the force commander concerned will decide whether the doctrine will be placed in one or two volumes.

D. Points to be Applied by Cruiser Divisions, Destroyer Divisions and Similar Forces.In basic organizations cruiser divisions and destroyer divisions are included in the Mobile Force, Diversion Attack Force, Night Operations Force, area forces, etc. These orders set forth doctrine for the Mobile Force and area forces and especially points to be applied in operations by cruiser and destroyer divisions.

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Matters based on doctrine and standard procedure (YOMU JUNSOKU) determined by Diversion Attack Force and Night Operations Force as in the past will be carried out so as to give full scope to the fighting power of such of the so-called light forces. Accordingly in establishing doctrine, combat regulations (SENSOKU) and standard procedure (YOMU JUNSOKU) force commanders will confer whenever necessary to prevent conflicting demands being made on cruiser division, destroyer division and similar forces.

E. Procedure for Determining Doctrine and the Like1. Force commanders will form board, and the boards at their discretion may order

specially designated commanding officers to carry out the work. It is sometimes wise to obtain the cooperation of naval KOKUTAI, schools, etc. At such times responsible commanding officers will take suitable measures.

2. When doctrine is determined, closest liaison will be maintained with Combined Fleet Headquarters. To coordinate concepts doctrine will be promulgated to all force commanders.

3. It is especially important to promulgate important matters without delay, if necessary in rough draft form.

F. Direction and Execution of Training1. Obviously these orders depend on a training of personnel organized basically

within fixed commands. For example, Commander in Chief, 3 Fleet will train cruiser divisions and destroyer squadrons of 2 Fleet in their capacity as elements of the Mobile Force, and Commander in Chief 2 Fleet will train cruiser divisions and destroyer squadrons of 3 Fleet in their capacity as elements of Night Operations Force and Diversion Attack Force. Consequently force commanders will lead ships of forces places under their command for operations in accordance with battle experience and a unified conception of the art of war and without regard to the fixed organization of the forces. A unified conception of the art of war is derived from doctrine, combat regulations (SENSOKU) and standard procedure (YOMU JUNSOKU) established beforehand. Training will be given at every opportunity so that operations may be carried out without hindrance of time or division of forces.

2. At first glance the contents of these orders are complex. However, because force commanders have been made responsible for putting the orders in effect, the possibility of confusion in their execution may cause anxiety. In practice, it is impossible to allow the orders to go into effect as they are. Because it is virtually impossible to carry out coordinated Combined Fleet training as in peacetime, each fleet headquarters will maintain close liaison with Combined Fleet Headquarters and with one another. In this manner they will provide for smooth training programs. When necessary, training will be carried out under Combined Fleet orders and all possible efforts will be made to put these orders into effect.

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G. Mobile Force Basic Organization Although it is expected that the organization of the Combined Fleet Mobile Force,

Especially Organization OTSU, will be under the immediate control of Commander in Chief Combined Fleet, basic organization will be in accordance with these orders.

H. Diversion Attack Force Basic Organization1. The character of the Diversion Attack Force is the same as that of the

former Advance Force. The old terminology was not suited to the style of present operations; therefore the designation has been changed to Diversion Attack Force.

2. It is anticipated that opportunities for the operations of the entire Diversion Attack Force as a single unit will be far fewer than for the Mobile Force. The Diversion Attack Force however bears some relation to the organization of amphibious groups (KAIJO KIDO HEIDAN) (temporary designation) which is presently the subject of special study. Some factors in Diversion Attack Force operations also require further study. In consideration of situations in which cruisers and destroyers are dispersed in a manner unusual according to the distribution of forces, the organization and commanding officer of the Diversion Attack Force will be clearly set forth. Suitable doctrine, combat regulations (SENSOKU) and standard procedures (YOMU JUNSOKU) (for example, formulation of combat regulations for engagement in narrow waters) and training will be established for each type of organization of those light forces. This organization will be established to facilitate the carrying out of operations. Accordingly, all cruiser divisions, destroyer squadrons and destroyer divisions of the Imperial Navy will establish their doctrine and the like in conformity with the doctrine established by the Diversion Attack Force Commander.

3. “Aircraft carriers will be added to the Diversion Attack Force” means principally that carriers will be added to assist in such matters as scouting. (A force which includes carriers with offensive power is a task force, therefore, when such carriers are added, operations are carried out in accordance with Mobile Force Doctrine). ii

I. Night Operations Force Basic Organization1. “Aircraft carriers to be added to the Night Operations Force” refers for

for the most part to carriers whose chief function is scouting. Further in cases where engagements begin as task force engagements and subsequently become night battles, the Night Operations Force will be responsible for the night combat and some of the aircraft carriers will come under its command. Co-operation and other necessary matters will be considered in terms of establishment of doctrine. (Night combat doctrine is needed even in Mobile Force Doctrine.)

2. In view of the fact that there are many opportunities for engagements in

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narrow waters, some of the essentials of night combat require re-examination if they are to be included as doctrine.

J. Advanced Expeditionary Force (SENKEN BUTAI) Basic Organization1. It is intended that submarine squadrons, submarine divisions, and individual submarines not included in 6 Fleet will be trained on the basis of unified concepts.

3. “Cruisers, aircraft carriers, etc, to be added to the Advanced Expeditionary Force” refers to suitable cruisers, converted cruisers and aircraft carriers, the chief function of which is scouting and which are added for such operations as destruction of sea traffic.

K. Base Air Force Basic OrganizationAt present base air forces operate in separate areas and on occasion place elements under command of another. In the future, however, they will operate as the Combined Base Air Force. Further, since units of all air fleets and air flotillas will be increasingly placed under the command of commanding officers of other forces, it is necessary to establish Combined Base Air Force doctrine, standard procedure (YOMU JUNSOKU) and doctrine suitable to all air flotillas, KOKUTAI, HIKOTAI and similar forces.

This basic organization is established in accordance with the above. To carry out and direct those provisions and the training relative to them is the responsibility of the base air force commander who is the senior commanding officer. He may make suitable commanding officers responsible for any necessary work as he sees fit.

Copies of his memorandum will be sent to all squadrons, flotilla and division headquarters and to all base headquarters.

8. OpOrd #40 sets out defense plans for SE, South seas, SW and NE areas indicating disposition of forces, operations for destruction and protection of sea traffic, for patrol and reconnaissance, communications policy, supply and repair, tabulating attached shipping units. Separate volume appended stipulates communications dispositions, procedure, and systems; dated 15 August 1943. This order and the three that follow were promulgated simultaneous with item 7 above.

9. OpOrd #41 sets out defense plans for Pacific Ocean Front; policy, procedure, detailed disposition and movement of forces for operations against an enemy attacking on the Pacific Ocean Front; dated 15 August 1943; Plan Z

10. OpOrd #42 Interception Zone Operations establishes Interception (Yogeki) Zones, the objectives therefore, bases to be constructed and forces to be disposed thereat. 15 August 1943.

11. OpOrd #43 Combined Fleet basic table of organization 15 August 194312. OpOrd #45 Corrections for an earlier order; 20 August 194313. OpOrd #46 Supply Organization; Supply points, advanced supply points and

advanced bases with standard quantities of material on hand thereat. 14. OpOrd #50 Submarine dispositions for Plan Z; 2 September 1943.

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15. OpOrd #52 Truk Flight Control Regulations; 1 September 1943.16. OpOrd #54 Allocation of Combined Fleet forces for Third Phase Operations; 20

September 1943. 17. OpOrd #55 Sets out defense plans for Indian Ocean Front including policy,

procedure, classification, distribution of forces, etc, for operations against an enemy attacking in the Indian Ocean Area, including a separate volume outlining Combined Fleet Communications plan for Plan Y: Plan Y dated 25 September 1943.

18. OpOrd #59 Revises third phase allocation of forces of Combined Fleet19. OpOrd #60 Wave Length to be used by “Ko” Type aircraft of “To” Operations

forces.20. OpOrd#61 Revised allocation of forces for Combined Fleet Third Phase

Operations, 5 December 1943.

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21. OpOrd #69 Revised Allocation of Combined Fleet as of 15 February 194422. OpOrd #73 Revised Plan Z. This was an outline operation order and is set out in

“Campaigns of the Pacific War” at p. 221. The Operation Policy for Plan Z is set out in paragraph D as follows; “The main operations will be directed at the Central Pacific Front. The area stretching from the Kurile Islands and the waters east of Honshu through the Nanpo Shoto, the Marianas and the Carolines to New Guinea in the west will be considered the interception zone, and the enemy fleets will be intercepted and attacked here. Enemy carriers will be put out of action first by a concentration of our air power. After air superiority has been achieved the attack will be directed against convoys. In some situations, the convoys will be attacked and destroyed first. Surface forces, in concert with these air attacks will raid enemy convoys or enemy fleets in important areas.” The emphasis on destruction of the enemy carriers is particularly noteworthy.

23. OpOrd #74 Revised Allocation of Combined Fleet as of 10 March 1944.24. OpOrd #76 Outline of A Operation. This is the basic operation order in effect

during the Marianas campaign and supercedes Plan Z above. It is set out in “Campaigns of the Pacific War” at pp. 226-231. It is much more expansive than Plan Z.

25. Dispatch: Admiral Toyoda assumes command of Combined Fleet. This message can be found at p. 233 in “Campaigns of the Pacific War”.

26. Standing Order #20 Detailed Tabulation of Division of Fleets of the Combined Fleet (see immediately following):

After taking over as Commander Combined Fleet Admiral Toyoda issued a series of orders. Most were the usual type but one is of interest since he moved their tactical/administrative table of organization formats towards those used by the U.S. Navy; not quite however. One notices immediately that unlike the USN Task Force formats, where units could be plugged into a task force table of organization without reference to their administrative assignment here the administrative assignment follows the squadron, ship, etc.

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COMBINED FLEET ULTRASECRET STANDING ORDER 20

Division of Fleets of the Combined Fleet

COMBINED FLEET

OYODO Unit #15

FIRST AIR FLEET

Air Flot 61 Unit # 1001Air Flot 22 Unit # 1002Air Flot 23 Unit # 1003Air Flot 26 Unit # 1006

CinC First Air Fleet will determine fleet division for remaining surface forces attached to First Air Fleet using Unit # 1061 to 1100

FIRST MOBILE FLEET

Second Fleet CruDiv 4 Unit # 24CruDiv 5 Unit # 25 CruDiv 7 Unit # 27Bat Div 1 Unit # 21Bat Div 3 Unit # 23Des Ron 2 Unit # 22

Third FleetCar Div 1 Unit # 31Car Div 2 Unit # 32Car Div 3 Unit # 33Des Div 10 Unit # 37MOGAMI Unit # 38

CinC 3rd Fleet will determine fleet division for remaining surface forces attached to 3rd Fleet using Unit # 35 to 36 and 2351 to 2400

CinC FIRST MOBILE FLEET will determine fleet division for remaining surface forces attached to First Mobile Fleet using Unit #2301 to 2350.

Sixth FleetSub Ron 7 Unit # 61Sub Ron 8 Unit # 62Sub Ron 11 Unit # 63

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CinC 6th Fleet will determine fleet division for remaining surface forces attached to 6th Fleet.

Northeast Area FleetFifth Fleet

Cru Div 21 Unit # 51Des Ron 1 Unit # 55

CinC 5th Fleet will determine fleet division for remaining surface forces attached to 5th Fleet using Unit # 2551 to 2600

12th Air Fleet

Air Flot 27 Unit # 1227Air Flot 51 Unit # 1251

CinC 12th Air Fleet will determine fleet division for remaining surface forces attached to 12th Air Fleet.

(under direct command of Northeast Area Fleet)

Cru Div 22 Unit # 52Kurile Island Area Base Unit # 57

Northeast Area Fleet will determine fleet division for remaining surface forces attached to Northeast Area Fleet.

Remaining portions omitted here.

A practical application of Standing Order 20 was Combined Fleet Ultrasecret Operation Order 79 issued 30 May to become effective 1 August (portions are omitted see below item 29).

27. Revised Allocation Third Phase Operations: Combined Fleet 28. OpOrd #78 Assignment of supply forces 29. Regulations for Identification of Combined Fleet Airplanes

REGULATIONS FOR IDENTIFICATION OF COMBINED FLEET AIRPLANES

. . .

COMBINED FLEET

Notes: 1. For unit (ship) names the ship (sequence) number will be added to the two digits of the unit code numbers given adjacent to the unit number raising the number of

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digits to three (When there is no need to add the ship number 0 will be added. 2. Airplane numbers will be sequential. 3. For example OYODO # 1 airplane will be 150-01 etc.

COMBINED FLEET

OYODO Unit # 15 color: Yellow

2nd Fleet (color White or Blue) Bat Div 1 Unit # 21 Bat Div 3 Unit # 23Cru Div 4 Unit # 24Cru Div 5 Unit # 25Cru Div 7 Unit # 27Des Ron 2 Unit # 22

3rd Fleet (color Red or Yellow)

Des Div 10 Unit # 37MOGAMI Unit # 38

(note: the Naval Air Groups were separate entities and numbered accordingly)

Balance omitted.

Note: For example battleship YAMATO was unit 211 (2nd Fleet; 1st Division; #1 ship) and its planes would be numbered 211-01 etc.

30. Standing Order #21 Identification codes for identification of Friendly Forces, dated 11 July 1944. 31. Special Order #42 Combined Fleet Regulations re Patrol Codes, dated 22 July 1944. 32. OpOrd #82 Regulations for Base Air Force Air Patrols, dated 1 August 1944. 33. OpOrd #83 Revises distribution list for Outline of Combined Fleet Operations. 34. OpOrd #84 Allocation of Forces revised for Third Phase Operations 1 August 1944. 35. OpOrd #85 Distribution List of Outline of Operations dated 4 August 1944. 36. OpOrd #86 Air Combat Regulations for Sho Operations issued 4 August 1944. 37. OpOrd #87 Outline for Advanced Expeditionary Force Sho 38. OpOrd #90 Revision of Combined Fleet Operations dated 24 August 1944. 39. OpOrd #91 Revisions of OpOrd issued 24 August 1944. 40. OpOrd #92 Joint Operations of Naval Forces dated 24 August 1944. 41. OpOrd #94 Additional Patrol Sectors Combined Fleet Air Forces dated 27 August 1944. 42. OpOrd #96 Amphibious Counterattacks Sho dated 1 September 1944. 43. Memorandum 27 on Operations Orders revised distribution list dated 1 September 1944.

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This list is certainly incomplete, but does show how bureaucratic navies are. The number of revisions to various standing orders, distribution lists, etc promulgated can be staggering to the uninitiated. It illustrates how much preparation is needed to do what appears to be the simpliest tasks.

9 Destroyer Doctrine and Procedure

At the beginning of the Pacific War the Japanese Destroyer force was among the best in the world. Though they did not fight the battles they had trained for their doctrine and procedure served them well for nearly two years. In a series of intense actions they matched and often overmatched their principal adversary, the U. S. Navy. By the end of 1943 the U. S. Navy had caught and in most respects passed the Japanese Navy in the skills that had served the Japanese so well.

The rewrite of Japanese Destroyer Doctrine and Procedure here was published by Admiral Kurita’s Second Fleet staff in December 1943. It is still a document that anticipates a big gun/torpedo action much like those practiced by both navies between the wars.

DESTROYER DOCTRINE

General PrinciplesThis Doctrine is based on Combined Fleet Doctrine, Diversion Attack Force Doctrine, Mobile Force Doctrine and Night Operations Force Doctrine.

Alert, Approach and Scouting

General Rules: When in a condition of alert ships will observe the following:Objective of Reconnaissance

Outline of Action: Cruising Outline of Action: at Anchor

Lookouts AirplanesSurface CraftSubmarines

A condition of alert (ship lookout disposition will be fixed.

Radar Surface CraftAirplanesTo maintain position of ship (when visibility is poor):navigation

Fixed dispositions will be established in accordance with special orders. They will be used when our forces are discovered or contacted by the enemy.

Radar Intercept Device

Interception of enemy radar

Manned as a matter of course from sundown to sunup and, at times, when visibility is poor. At times by special orders, combined watch

By special order, combined watch

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Hydrophone Surface craft (at times of poor visibility)TorpedoesSubmarines

Manned at all times by special order, combined watch

By special order

Echo Ranging Gear

SubmarinesTo maintain position of ships (when visibility is poor): navigation

Combined watch when proceeding at 5 knots or less

By special order

Exploitation of enemy signals

InterceptionTo determine bearings. To discover enemy strength, movements and plans

To be carried out in accordance with communications regulations

Orders for Cruising under Alert (Keikai Koko)When a destroyer squadron is proceeding to attack independently it will take precautions against enemy aircraft and submarines and prepare to meet enemy surface forces.The usual zig zaging will be carried out except in especially poor visibility.The orders for cruising under alert and their application are as follows:

Order of Cruising Under Alert 1

Screening Unit

C C

D

C C

A

B

Notes: A=3km; B=1km; C=2km; D=3km

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The units will take station on the flank on which they are proceeding.In the screening unit formation, changes will be possible except with DThis order will usually be used during the day.

Order of Cruising Under Alert 2 E

B

D

C

A

B

Notes: A=3km; B=1km; C=2km; D=5km; E=5kmThis is a night cruising orderD & E will be maintained as indicated in the order. The disposition of strength will be fixed by the commanding officer of the screening unit.The units will take up station on the flank on which they are proceeding.

Order of Cruising Under Alert 3

Notes:A=3km; B=3km; C=2km

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In the absence of special orders the stations will be as follows:

Unit Number Station Number1 13, 1, 3, 52 2, 4, 6, 143 15, 7, 9, 114 8, 10, 12, 16Notes: If any of the units are lacking the required number of ships positions 13, 14, 15 or 16 will be omitted. The angle of station may be change, which change will be reported.This is a day order.

Order of Cruising Under Alert 4

Same as 3 except that left is interchanged with right.

Entering and Leaving Harbor will be done quickly and secretly while keeping a strict lookout for submarines, mine laying airplanes and torpedo boats. Paravanes will be streamed. In the event magnetic mines are suspected waters of less than 80 meters should be avoided. Areas suspected of enemy submarine activity (typically within 100 miles of the harbor mouth) a speed of 20 knots or more should be maintained.

Temporary Anchorage in Enemy Waters. In such cases strict alert should be maintained. Selection of such anchorages are determined using the following criteria:Anchorage in group or separatelySecurity and PatrollingAdherence to reconnaissance planEngine readinessTactics at time of enemy attackDefenseWhen anchoring where there is danger from enemy mines degaussing will be used even when at anchor. If necessary sweeping will be carried out.

Approach

Parallel lines with the flagship at the head will be normally used as the order of approach.

Order of Approach 1

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A=1km; B=1km; C=4km. May be lengthened if situation merits. Stationing the flagship at the center of both units will be an alternate method.

Order of Approach 2: Same as 1 except the flagship will be at the head of the left column.

Order of Approach 3:

A=5km; B=5km. This is a night order of approach

Scouting: Scouting will be the primary responsibility of airplanes. Scouting by ships will be conducted in accordance with the following:

TYPES OF SCOUTING DISPOSITIONSScouting Disposition 1

Scouting Disposition 2

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Scouting Disposition 3

Scouting Disposition 4

Scouting Disposition 5

Scouting Disposition 6

Scouting Disposition Notes:Each unit will maintain its relative position and proceed in the indicated direction at the designated speed.The type of scouting disposition, base course, speed and interval will be ordered when scouting is to begin. Unless otherwise ordered a will be10 km and the base course and speed will be the same as at the time action begins. The line of scouting dispositions will be at right angles to the course being followed.Unless otherwise ordered the flagship will be the guide.The flank on which a unit will be stationed is determined by its station at the time the maneuver begins. In case of doubt, special orders will be issued.The station of each unit will front on the base course and will be indicated by unit name in order from the right.

Combat policy in day action is to close in on the enemy and destroy it. At night it is to destroy the enemy in one stroke. In task force operations assist in developing the fighting power of the raiding air groups

Combat MethodsType Outline of Combat NotesCombat Method

A position of readiness will be assumed, in coordination with the

Action on same course A (Ko) will be in a deployed formation. Action on

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1 main body. Then the entire force will attack.

same course B (Otsu) will be in close order. The alternate method will be the same except it will be action on opposite course.

Combat Method 2

There will be a quick deployment. Following the lead of the flagship, each unit will enter the fight and close in. At the opportune moment the entire force will attack.

The alternate method will be the same except it will be an action on opposite course.

Combat Method 3

The entire force will shift to the attack upon meeting the enemy (unexpectedly or otherwise).

Action on same course-Ko: Upon meeting the enemy (unexpectedly or otherwise) the leading unit will use O type firing. There will then be a shift to formation for an action on same course and an attack will be carried out. The alternate action will be the same except it will be on opposite course

Combat Method 4

A quick deployment (assumption of attack disposition), O type firing will be used to decoy the enemy. The entire force will shift to the attack when torpedoes have had time to reach their targets.

The alternate method will be the same except action will be on opposite course.

Combat Method 5

A line up in order of battle (attack disposition) will be effected. Shift to the attack will be made in support of the attack of other friendly forces (air forces, O type firing by cruiser forces, etc.)

The alternate method will be the same except action will be on opposite course.

Combat Method 6

Attack dispositions will be assumed after the enemy delaying force has been destroyed.

-Action on Same course KO. While a portion of the force attacks the enemy delaying force, the rest will assume attack dispositions.-The alternate method will be the same except action will be on opposite course.

Combat Method 7

Each unit will assume attack dispositions undetected by the enemy. In accordance with orders, the entire force will shift to the attack.

The alternate method will be the same except action will be on opposite course.

Combat Method 8

One element will divert the enemy. The major portion will assume attack dispositions undetected by the enemy. At the opportune

-Action on Same Course KO. The flagship and designated units (or airplanes) will illuminate the enemy brightly. The remainder will take

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moment the entire force will shift to the attack.

advantage of this and attack. Then the entire force will attack. -The alternate method will be the same except action will be on opposite course. -General method for diverting the enemy; Designated units will fire their guns, lay down smoke screens, transmit radar waves, use searchlights, etc.

Combat Method 9

A night engagement will be carried out in force in accordance with the outline for night engagements

The alternate method will be the same except that it will be action on opposite courses.

Combat Method 10

For a time a long range frontal engagement will be carried out or the enemy will be decoyed toward friendly forces.

The alternate method will be the same except that it will be action on opposite courses.

Day EngagementsFleet ActionsOutlineStrikes by Groups (Shudan)Signal:Windsock - Blackball

Strikes by Deployment will be conducted as follows:Signal:Windsock - Course Signal

Day Engagements with Enemy ForcesOutline

Order of Battle

Type Order Remarks1 Flagship

DesdivDesdivDesdivDesdiv

In order of unit numbers; however, when forming from a parallel formation, the units coming together from the disengaged side will follow the units coming from the engaged side.

2 (Screening Unit)DesdivFlagshipDesdivDesdivDesdiv

Destroyer Divisions will be in numerical order. However when forming from a parallel formation, the units coming together from the disengaged side will follow the units coming together from the engaged side.

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3 DesdivDesdivFlagshipDesdivDesdiv

When forming from a parallel formation, the units coming together from the disengaged side will follow the units coming together from the engaged side.

4 Generally the existingCruising order

Night engagementsNight engagements in open seaOutlineTrackingDestruction of enemy delaying force

Attack Dispositions

Type Disposition Sketch Outline1

Notes: In the absence of special orders: The Otsu Unit will consist of 1, 2, and 3 Units. The senior division commander will be the commanding officerKo Unit will consist of the flagship and sec. 2 of 4 UnitHei Unit will consist of sec 1 of 4 Unit

The main operation will be the surprise attack by Otsu Unit. Each force will strike in concert with that attack.Ko Unit will be responsible for decoying the enemy if necessary.Hei Unit will be responsible for tracking.D represents the field of vision or the range limit of detection by ranging equipment. In the absence of special orders D will be 15km

2 The enemy will be decoyed by Hei Unit. Each unit will attack simultaneously and enemy withdrawal checked.Hei Unit will divert the enemy by gunfire and radar or by laying down a smoke screen. The remaining forces

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Notes: In the absence of special orders:Ko Unit will consist of flagship and 2 Unit.Otsu Unit will consist of DesDiv Group 1Hei Unit will consist of Sec 2 of 4 UnitTei Unit will consist of Sec 2 of 4 Unit (t.n. sic)*

will preserve secrecy.Tei Unit will make contact.D represents the field of vision or the range limits of detection by ranging equipment. In the absence of special orders D will be 15km.

3

In the absence of special orders:Otsu Unit will be Desdiv Group oneHei Unit will be 2 Unit.Tei Unit will be 4 Unit

The main operation will be the surprise attack by Otsu Unit. Each unit will make the attack in support.Depending on conditions, the flagship will take up its position either in the lead of Otsu Unit or Hei Unit.D represents the field of vision or the range limit of detection by ranging equipment. In the absence of special orders D will be 15 km.

4

In the absence of any special orders:Otsu Unit will consist of sec 1 of 4 Unit.

When the enemy is encountered, stations will be taken immediately on the enemy bow at the limits of the enemy field of vision or at the range limit of detection.Torpedoes will be appropriately fired without enemy knowledge. Units will then retire together from the scene of action.Depending on the results of the torpedo attack, the entire force will strike in accordance with the outline for strikes by deployment.Ko Unit will take up its position in the order of battle.Otsu Unit will be responsible for tracking and will serve as a threat to any enemy withdrawal.

5 Remaining together the force will proceed outside the enemy field of

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vision or range of detection. The enemy will be attacked from one flank in accordance with the outline for day strikes (in the absence of special orders, strike by deployment) Basic striking course will generally be ordered.The flagship will operate in accordance with the situation of enemy screening units.

6

In the absence of special orders:Otsu Unit will be DesDiv Group 1Hei Unit will be Des Div Group 2

Units on either flank will proceed outside the field of vision and the range of detection(In the absence of special orders this will be 30 km).Depending on the situation the flagship will operate at the head of DesDiv Group 1 or DesDiv Group 2.The interval between DesDivs may be extended as the senior division commander of either DesDiv Group sees fit.D represents the field of vision or the range limit of detection by ranging equipment. In the absence of special orders D will be 15km.

7

In the absence of special orders:Ko Unit will be the center unitOtsu Unit will be the right flank unitHei Unit will be the left flank unit.

It will be customary to transfer from scouting disposition to attack dispositions.Units will come in for attack on opposite courses.The flagship may operate in the center or on one extremity of the scouting disposition, depending on the situation.A shift to disposition on same course will be made without orders when it is difficult to commence action on opposite course because of enemy withdrawal.In the absence of orders A will be 10 km and B 18 km

8 Ko Unit will operate so as to contact the enemy in the vicinity of the field of vision and the range limit of detection. It will be responsible for guiding Otsu

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In the absence of special orders;Ko Unit will be the flagship and sec 2 of 4 UnitOtsu Unit will be DesDiv Group 1Hei Unit will be DesDiv Group 2 less sec 2 of 4 Unit.

and Hei Units and will set in consert with their attack and check enemy withdrawal.Otsu and Hei Units will proceed and deploy across the enemy course (about 35 km) outside the field of vision and range limits of detection operating under the command of the senior division commander. Once deployed all will resume the basic course.D represents the field of vision or the range limits of detection by ranging equipment. In the absence of special orders D will be 15 km.

9 Attack disposition when employing smoke screen.When operating in an authorized attack disposition, units other than the tracking unit will have their rear ships move in and proceed abreast, laying a smoke screen at the limits of the enemy field of vision. Smoke screen laying will be discontinued with the order “Prepare to strike”. Ships will then return to their assigned units.Each unit will proceed under cover of smoke screen with the ships which have laid the smoke screen in the lead. With the order, “Prepare to Strike” each unit will slip through the smoke screen and strike.

The order for this attack disposition will be issued if this disposition is to be in force simultaneously with other attack dispositions.Vessels laying the smoke screen will report the enemy situation.

Dispositions 1-4 provide for alternate dispositions by exchanging left for right. Also note that the general method for each disposition is set forth. The form will not be inflexible in any case. Operations will immediately correspond to changes in the situation.

Night Engagements with Enemy Light ForcesNight Operations in Narrow Waters

i

12. Southern Forces Orders

I don’t have this volume ii

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COMBAT REGULATIONSTorpedo ActionStandard Plan for FiringDay (Decisive Battle):Item Type 93 Type 93 Type 90 Type 90 Type 8th

YearType 8th Year

Cruiser Destroyer Cruiser Destroyer Cruiser DestroyerSpeed Setting

Speed 1 Speed 1 Medium Medium Medium High

Range Full Full Full Full Full FullLaying Range

8,000-10,000m

8000m 8000m 8000m 8000m 8000m

Depth Setting: Capital Ships: 6m (Cruisers sometimes use second setting; Capital Ships and Aircraft Carriers; 5m; Cruisers and aircraft carriers; 4m; Destroyers 3m

Point of Aim: Center ship of unit under attack (if there are four ships-Second ship.

Night (during attack)Item Type 93 Type 90 Type Type 8th YearSpeed Setting

2 Cruiser: mediumDestroyer: high

High

Range Full: When friendly units on opposite side range will be reduced by about half of full range

Full Full

Laying Range

5000-6000m5000m destroyers

5000m 2000m

Point of Aim

Center ship of unit under attack (If four ships second ship; Amidships of single ship

Amidships of single ship

Amidships of single ship

Note: Depth setting: same as day settings.

Secret Torpedo Action: Unless specifically ordered Ko will be ordered.Classification Ko OtsuItemTorpedo Speed1

1 2

Laying Range About the limit of effective range for enemy medium and small caliber guns

About the limit for visual and radar ranging (about 25,000m

Notes to Secret Torpedo ActionDepth Setting: Against Capital Ships and a group of cruisers 5m; Against groups of cruisers 4m; Against groups of cruisers and destroyers 3m.

1 Torpedo Speed 1 is 49 knots/range 20,000 meters; Torpedo Speed 2 is 36 knots/range 40,000 meters.

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Point of Aim: In firing, the following will be used as standard or basis for direction; Silhouette or searchlights of enemy ship, Parachute flares dropped by friendly airplanes, Electric ranging and direction by friendly airplanes.Disposition According to Situation: The various units will be chosen depending on whether they are proceeding directly or approaching. When Forward of the beam the unit next ahead (Sec 1) will proceed directly and the following unit (Sec 2) will then approach. When abaft the beam, the opposite procedure will be followed.Number of Fired Torpedoes: Half of full firing line.

Gunnery EngagementsClassification Sketch

Examples Outline of Forming in Gunnery Engagement Formation

Gunnery EngagementFormation

Enemy* Pre arranged signal: 1 Jin Otsu 2 (L) Gin (2)Form in gunnery engagement formation with interval of ____bear to right (left)Outline:The right (left) flank destroyer divisions will adopt the interval shown on the right (left) (In the absence of special orders the interval will be 3km)If necessary base course will be indicated. In the absence of special orders, it will be the course at the time orders are issued.When there are three destroyer divisions one will proceed to the flank where the flagship is stationed, and the interval adopted will be about 3k. In these circumstances when the flank divisions, the leading division will proceed astern of the flagship, and the following division will proceed astern of the destroyer division on the opposite flank.

GunneryEngagementFormationAlternate Method

Enemy* Pre arranged signal: Jin Otsu R (L( BankeiMessage: Form in gunnery engagement formation with interval of _____km to right (left) alternate method.Outline:The ship at the head of the destroyer divisions on the right (left) flank will draw abreast of the ship at the head of those on the left (right) flank, otherwise the same is the proceeding.

*Sketch examples below:

DESTROYER PROCEDURE

The standard amount of time consumedincreasing or decreasing formation speed is as follows:

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SPEED 12Standard

14Std

16Std

18Full

21 Battle Speed 1

24BS1

26BS 2

28BS 3

30BS 4

32BS 5

Standard amount of Time to increase or decrease speed (min/sec)

1-0 1-0 1-0 2-30

2-30 2-30

2-0 2-30

3-0 4-30

Total Time expended (min/sec)

1-0 2-0 3-0 5-30

8-0 10-0

12-30

15-30

20*

*There is some overlap beginning at Full Speed/Battle Speed 1 thus the opening at BS4.

This standard is the time it takes the main shaft to attain the number of RPM for a specified speed.This standard also applies to the amount of time required to increase or decrease the speed of a warship cruising independently.

10 (a). CarDiv 4 Doctrine

Carrier Division Four Doctrine: Since this is the only pre 1943 doctrine in the NACHI find and one that pertains to Japanese carriers in 1941-2 it is worth setting out in full. A brief summary of Carrier Division Four operations is also in order.

Carrier Division Four (Dai Shi Koku Sentai 4sf) was organized in April 1941 when the carriers were placed under one administrative organization, First Air Fleet (Dai Ichi Koku Kantai). At the time it was organized Carrier Division Four consisted of carrier RYUJO and her destroyer screen. From April until early November RYUJO operated in the central Pacific returning to Kure in the home islands on November 10, 1941. On November 27 while still in Kure Admiral Kakuta, commander Carrier Division Four issued Ultrasecret Standing Order 20, Carrier Division Four Doctrine. This was the same day the Pearl Harbor Strike Force, First Mobile Force (Dai Ichi Kido Butai or 1KdB) departed Japanese home waters for the attack which would open hostilities between the U. S. and Japan. One hundred copies were issued with one going to NACHI. When operating as a tactical unit 4sf would become Second Mobile Force (Dai Ni Kido Butai or 2KdB).

During this period light carrier SHOHO entered service. She was attached to 4sf on December 22, 1941 remaining in home waters working up until early February.

While SHOHO worked up RYUJO was very active supporting the Philippine invasion from the outbreak of the war until December 26. In early January she operated out of Camrhan Bay in support of the Malay operation. In February she was assigned to the forces attacking the Netherlands East Indies. In March she continued supporting

49

operations in the Malay and Burma areas, operating there until April when she returned to Japan for a drydock period before AL (Aleutians).

During this period SHOHO moved between Truk and the Empire before participating in Operation MO when she was lost in the Battle of Coral Sea. At no time during her period of service did SHOHO operate with RYUJO as a tactical unit.

On May 3, 1942 after her commissioning carrier JUNYO joined 4sf, just in time for Operation AL. This was the one time 4sf had two carriers.

Following the Midway disaster First Air Fleet was disbanded and the carrier divisions reduced to two, both being assigned to Third Fleet (Dai San Kantai). On July 14, 1942 4sf was disbanded and its two ships joined JUNYO’s sister HIYO to form Carrier Division Two (Dai Ni Koku Sentai 2sf)2.

In 1944 Carrier Division 4 was reformed, but that formation had nothing to do with the 1941-2 version.

Here follows the bulk of Carrier Division 4 Doctrine:

Carrier Division 4 (4sf) Doctrine, 27 November 1941

I. General Principles In this Doctrine are set forth the plans and policies to be adopted by CarDiv 4 before, during and after combat and those matters to which each ship will conform. Each commanding officer is expected to do his utmost to conform to this doctrine and to apply the instructions contained in the “Naval Combat Regulations”3 and in the various manuals.

II. SecurityA. Cruising Under Alert (Keikai Koko)1. The orders of Cruising under alert are as follows:

Order of Cruising Under Alert 1

Order of Cruising Under Alter 3

Order of Cruising Under Alert 5

Order of CruisingUnder Alert 7

(1) D=3kBase course

Base Course

45 (1)

Base Course

Limit of

Base Course

(0)

2This brief outline of the operations of 4sf is from several sources: Imperial Japanese Navy in World War II, a graphic presentation of the Japanese Naval Organization and List of Combatant and Non-Combatant Vessels Lost or Damaged in the War, Japanese Monograph 116; Tabular Records of Movements of Japanese warships found on the Nihon Kaigun website, http://www.combinedfleet.com and various popular histories. 3 Not recovered in NACHI group.

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(0)

D=3k

(0)

Visibility 90

(0) (1)

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(1)

Order of Cruising Under Alert 2

Order of CruisingUnder Alert 4

Order of Cruising Under Alert 6

Order of Cruising Under Alert 8

(0)

Base Course

D=3k

(1)

Base Course

(1)

D=3k

45

(0)

Base Course

(1) (0)

Limit of Visibility

Base Course (0)

45

(1)

Notes:Cruising Order 5 (6): In absence of special order D will be equal to the limit of visibility. The destroyer will maintain especially strict security to starboard (port).Cruising Order 7 (8): In the absence of special order D will be equal to the limit of visibility. The destroyer will maintain especially strict security to the starboard (port) quarter.4

B. Air Security1. Patrol of the Route of Advance

Type of Disposition

Disposition 1 Disposition 2 Disposition 3 Disposition 4

Number of AirplanesOperating atOne time

One Attack Plane

One Attack Plane

Two Attack Planes

Three Attack Planes

4 USF 77 CURRENT TACTICAL ORDERS, AIRCRAFT CARRIERS U.S. FLEET (3-41) contains provision for four plane guard stations: Flight stations, night operations, day operations (high visibility) and day operations (low visibility). Otherwise they are not substantially different from the Japanese method.

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Diagram ofMovements

Outline of Patrol Operations: Duration of one patrol will be three hoursDatum Point “O” will be fixed by special orderIn the absence of special orders the base course will be the course at the timeIn the absence of special orders the patrol range “D”, interval between patrol lines “b” and measurement “d” will be as indicated in the diagram. Each airplane will patrol by following the movements of the diagram and reversing them within the prescribed time. The altitude of the airplane will be determined by the airplane (unit) commanderWhen enemy submarines are being neutralized or enemy ships and boats tracked, the duration of the patrol will be four hours.Special orders may assign two airplanes to each patrol line

2. Direct Antisubmarine EscortType of Disposition

Disposition 1 Disposition 2 Disposition 3

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Number of Airplanes Operating atOne Time

One attack plane Two attack planes Four attack planes

Diagram of Movements

Duration of one patrol will be approximately three hours, relief will be made at a designated position. Standard altitude will be 300-500 metersThe airplane (unit) commander may so reduce his range from the ship (or ships) being directly escorted that he will be within sight when visibility is reduced. The movements indicated in the diagram will be based on the ship (ships)When enemy submarines are detected they will be attacked and neutralized. At the same time the prescribed report will be sent to lead the direct escort destroyers to the spot.5

5 U. S. practice was quite similar. See USF 74 (Revised) Current Tactical Orders Carrier Aircraft (3-41) section 1-536: Intermediate air patrol is defined as protection against enemy submarines, preventing them from gaining favorable attack position. 2-3 plane units search 30 degree sub sectors 60 degrees either side of base course (4X3 aircraft). The depth of the search is 40 miles out and flown at no greater height than 2500 feet. Both navies working assumption seems to be based on limiting lines of approach, that is to say, if the submarine isn’t somewhere between 45 degrees and 60 degrees of the carrier’s base course, assuming the carrier is making good speed, it will not be able to get into firing position. In both cases this is good doctrine with the American doctrine being somewhat more conservative .

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2. Security against Trailing Enemy SubmarineType of Disposition

Disposition 1 Disposition 2 Disposition 3

Number of Airplanes Operating atOne time

One Attack Plane Two Attack Planes Two Attack Planes

Diagram

Of

Movements

Outline of Patrol OperationsDuration of one Patrol will normally be three hoursIn the absence of special orders the rear ship of the group will be the base shipIn the absence of special orders the course at the time will be the base courseThe patrol will attack and sink enemy submarines, in accordance with movements indicated in the diagram.6

4. High Altitude Direct Escort (CAP)

Type ofDisposition

Disposition 1 Disposition 2 Disposition 3 Disposition 4

Number ofAirplanes OperatingAt One Time

Three FighterPlanes

Six FighterPlanes

Nine Fighter Planes

All FighterPlanes

Standard Altitude 4,000 meters Lower Level3,000 metersUpper Level4,000 meters

Lower Level3,000 metersMiddle Level4,000 metersUpper Level5,000 meters

(By special Order)

6 No American equivalent. When the threat from a trailing submarine is set against available resources the American practice makes more sense.

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Outline of Operations:Duration of one patrol will be two hours. The succeeding patrol will automatically be first group (or by special orders the second group) of alerted airplanesRelief of each patrol will be at assigned positionsSecurity area: generally within the limits of the whole field of vision over the ship (or group of ships) being directly escorted. As a basic rule the, the ship command of the high altitude direct escort will be aboard the carrier. Exceptions will require a special orderThe high altitude direct escort will patrol in fighter unit formation. The commanding officer may alter the altitude to suit the ceiling and field of vision.7

5. Anti Aircraft PatrolIn the orders to the anti aircraft patrol planes, the assigned areas, the take off time of the airplanes, the duration of the patrol and the range of the patrol “D” will specified.

Diagram of Assigned Areas

Patrol OutlineThe patrol aircraft will move around the circumference of the assigned area, keeping a sharp watch for enemy airplanes and sending in patrol reports (warnings)As a general rule one plane will be assigned to each sectorPatrol altitude will be 3,000 to 4,000 metersIn the absence of special orders “D” will be 20kmIn going back and forth between assigned points, anti submarine patrol also will be carried out.8

C. Identification of Friendly Forces

7 USF 74 section 1-539 establishes two types of “Combat Patrols” (later Combat Air Patrol); 1. patrol of 4-6 VF, “if enemy bombing attack are anticipated it may be necessary to retain the entire fighter strength as one patrol relying on aerial pickets to report enemy aircraft in sufficient time for the patrol to engage the bombers before they have delivered their attack (pre radar 3-41). 2. To deny enemy observation 3-4 VF patrol to thwart enemy VS. Altitude 7,000-10,000 feet in both cases. 8 USF 74 section 1-535 describes Outer Air Patrol as 3 plane units flying along chord of sub arcs of a 20 n. mile circle, “only that part of the circle from which attack is expected normally will be patrolled.”

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III. Search, Reconnaissance and TrackingSearch Methods

Method 1 Method 2 Method 3 Method 4 Method 5

Diagram ofSearch Methods

Outline for Execution of SearchBy special order the basic search line begins at datum point (0), Range is “D”, lateral distance is “d”, angle is “o”, area is (1)Normally one airplane is used in the search line. If two or more airplanes are assigned a special order is required.In the absence of special orders each search plane will return to the datum point according to the outline of movements in the diagram.When the number of search lines is greater than the number on the diagrams, each side will be added to successively and when less than the number on the diagram the lines in excess will be deleted successively.9

IV. Combat

A. Combat PolicyThe main object will be to destroy the enemy forces in a particular area immediately with all of our power. To this end the greatest possible mobility will be employed, and the airplanes available will be used extensively and aggressively.Friendly forces will be protected by keeping a strict alert against airplanes and submarines and by seizing the initiative and destroying those that are discovered. The particular vulnerability of aircraft carriers will be kept in mind.The policy is that aircraft carriers will not engage in combat with surface ships except when especially necessary or under especially favorable conditions. While aircraft carriers are escaping from surface ships, the latter will be destroyed by airplanes and destroyers. The destroyers will place themselves quickly between the aircraft carrier and the enemy concealing the carrier, and at a favorable opportunity, will counterattack.

B. Air CombatThis command will order air combat.

9 See USF 74 section 2-101 et seq. There is little difference between the two navies on this subject.

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Although the outline of organization, object of attack, weapons to be used and movements will be ordered by this command when an attack unit is sent out, the attack will be executed under the command of the attack unit commander.In an air attack complete success will be attained by greatly shortening combat distance and using the time gained to make sudden and repeated attacks.In an attack when resistance by airplanes is expected, the fundamental policy is to gain control of the air by use of fighter planes and attack under their protection. Nevertheless, in certain cases, attack plane units only will attack on moonlit nights at dawn and at dusk. The principal object of the high altitude direct escort unit will be to engage raiding airplanes in combat outside the range of anti aircraft fire and before they attack. The attack must first be concentrated on the airplane of the enemy commanding officer (the guide airplane). After the enemy attack maneuvers are disorganized, his airplanes will be destroyed one after another. Our direct escort dispositions must not be weakened by over concentration of strength on one objective or sustained pursuit of airplanes after an attack.

The attack unit will be organized as follows:Organization Component forcesOrganization 1 Fighter Plane unit

Attack Plane unitVF-full strength VT-full strength

Organization 2 Fighter Plane unitAttack Plane unit

VF-9VT-9

Organization 3 Fighter Plane unitAttack Plane unit

VF-full strengthVT-3

Organization 4 Attack Plane unit VT-full strengthOrganization 5 Attack Plane unit VT-6

Command to be fixed by the captain of the aircraft carrierFull Strength is the number of airplanes available at present but will not exceed the number normally used. Organization for cases other than those listed will be given by special order.

Standard of weapons used in attack will be as follows:Attack Objective Bombs Notes Battleships No. 80

Ordinary807 kg bomb capable of penetrating 70mm of armor

Aircraft Carriers No. 25 Ordinary

248 kg bomb capable of penetrating 50mm of armor

Cruisers No. 25 Ordinary

Same as above

Submarines No. 6 Mk. 2 63 kg bomb Small warships(shipping) other than those listedabove

No. 6 Ordinary 63 kg bomb capable of penetrating 25 mm of armor

Especially No. 25 Land 258 kg bomb

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strongBuildingsAirfields No. 6 Land

No. 7 Mk. 669 kg bomb

Others No. 6 Land 67 kg bomb

Bomb notes: the weight and penetration characteristics are from the Naval Technical Mission to Japan Report O-23 “Japanese Bombs” and are not in the NACHI find. Such items as optimum altitude for dropping etc are not in the report.

Torpedoes: Torpedoes will be used against cruisers and above according to special orders. Torpedo Data:Fixed speed 42 knotsFixed depth: Battleships 6 meters, Cruisers 3.5 meters C. Gunnery EngagementsDay Gunnery EngagementsGunnery engagements will be opened at the most extreme range promising good results.Although the main function of the flagship normally is considered to be the directing and ordering of fire, this will be left to the discretion of the individual ship captains where rapid antiaircraft or anti submarine fire is necessary at a time when the flagship is itself firing.Firing by destroyers will be left to the discretion of the commanding officers.

Night Gunnery EngagementsIn case enemy ships, boats or airplanes are discovered at night, normally they will be avoided insofar as possible. However under certain circumstances an attack with the aid of illumination will be made.Normally illumination and gunfire will be executed by order, but, when speed is necessary, it will be left to the discretion of the ship captains (commanders).

D. Torpedo EngagementsTorpedo engagements, except those carried out by airplanes, will be carried out by destroyersStandard Plan for Destroyer Torpedo AttacksTorpedo Firing Data

TorpedoSpeed (knots)

DistanceSetting (meters)

Depth Setting (meters)

SightingRange (meters)

Day 32 9,500 Capital Ships 6 m 4,000Night 36 6,000 Cruisers 4m 2,000

E. Depth Charge ActionDestroyers will carry out depth charging.

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V. ProcedureA. Battle SpeedsBattle speeds for a given unit will be as follows:Battle Speed 1=18 knotsBattle Speed 2=20 knotsBattle Speed 3=22 knotsBattle Speed 4=24 knotsBattle Speed 5=28 knotsMaximum Battle Speed=Maximum speed of which each ship is (unit) is capable.

B. Smoke ScreensNormally smoke screens will be laid by destroyers. Sometimes they will be laid by the carriers themselves.The laying of smoke screens by destroyers will be left to the discretion of the commanding officer of the destroyer division. Normally the laying of a smoke screen by a carrier will require special orders. C. Methods of Airplane Standby

Type of Standby

Essentials Outline of Stand by

ImmediateAlert

Preparations willbe completed for animmediate take off

1. All personnel aboard the airplanes engines warmed up.2. Airplane (ground) crews at their assigned posts

Alert 1 Preparations will be completed for a take off within one minute after receiving orders.

1. All personnel aboard the airplanes engines stopped but kept in warmed up condition

Alert 2 Preparations will be completed for a take off within 10 minutes after receiving orders.

1. All personnel gathered together standing by in a convenient spot for receiving orders.2. Airplane crews standing by in the vicinity of the airplanes. 3. Trial warm-ups completed; airplane ready to start moving immediately

Alert 3 Preparations will be completed for a take off within 30 minutes after receiving orders.

1. Crew standing by in a convenient spot.2. Trial warm up of airplane begun depending on circumstances. May be ready in hangar.

Alert 4 Preparations will be completed for a take off within two hours after

59

receiving orders.10

D. Panel Signals from aboard Ship to Direct Escort Planes Overhead Panel signals from aboard ship to Direct Escort Planes

No. Signal Panel Message1 Enemy airplanes in this direction2 Increase altitude enemy airplanes in this direction3 Decrease altitude enemy airplanes in this direction4 Breakdown in radio (telephone) apparatus aboard ship5 Land on the carriers

Notes: 1. Panels will be made of sailcloth or thin boards, white in color and will be

divided into two kinds; long and short, and standardized as follows: Long; width 1 meter, length 4 meters. Short; width 1 meter, length 2 meters

2. Positions for stretching signal panels: Aircraft carriers; Flight Deck, Others ships and boats, on the deck forward of the forward bridge or on a gun turret.

3. With signal panels which indicate the direction of enemy airplanes the head of the letter T will be pointed in the direction of the enemy airplanes.

This doctrine is the only one recovered from NACHI that predates the Solomons campaign. It also was issued pre-radar. At that time the carrier was recognized as a weapon of powerful offensive capabilities, yet extraordinarily weak defensively. Both its defense and offense were the responsibility of its air group. The Japanese solution to this problem was to concentrate its big carriers into a single unit, first of four ships and, by the time of Pearl Harbor, six. By doing this they were able to allocate sufficient resources to all of the tasks outlined in this doctrine. Certainly one or two small carriers could not match their larger sisters. In fact this doctrine when matched with the resources available to execute it goes far to illustrate the genius of the decision to concentrate their big carriers. It also illustrates the need to keep that concentration. To do otherwise meant corners would be cut. If an objective was not worth committing all six carriers none of them should be committed. Of course the smaller force could conduct operations where the larger group was not needed. To carry out all of the tasks set out herein would require: Patrol of route of advance; 1-3 VT, Direct antisubmarine escort; 1-4 VT, Security against trailing submarines; 1-2 VT, High altitude direct escort; 3-9 VF, Anti aircraft patrol; 8 VT, Air search; 2-4 VT, Attack units; 3 or more VT and 9 or more VF. With the exception of air search these figures would be very similar for the large carriers, bus spread among the six ships. For contemporary Japanese tables for the larger ships see the treatment of Pearl Harbor in “Campaigns of the Pacific War”, pp. 23-24.10 USF 77 section 302. Airplanes may be ordered to assume a condition of readiness irrespective of that under which the parent ship operates. Condition 1: Airplanes kept warmed up, Flight personnel in flight clothing, in possession of latest available information of the tactical situation. Personnel and equipment ready to permit launching on 10 minutes notice. Condition 2: Personnel and equipment in readiness to permit launching on 20 minutes notice. Condition 3: Personnel and equipment in readiness to permit launching on 30 minutes notice.

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It should not be surprising that U. S. Navy doctrine was quite similar.

Note: Air Groups on board Carrier Division 4 ships December 1941-June 1942:

RYUJO:December 1941: 16 VF; 18 VT=34 totalJanuary-March 1942: 22 VF; 16 VT=38 totalApril 1942: 16 VF; 20 VT=36 totalMay 1942: 16 VF; 21 VT=37 totalJune 1942: 16 VF; 20 VT=36 totalSHOHOJanuary-May 1942: 16 VF; 12 VT=28 totalJUNYOJune 1942: 16 VF; 24 VB=40 totalNote: some or all of RYUJO and SHOHO VF were A5M during part of this period. The other VF were A6M , the VB D3A and the VT B5N.

10 (b) Cruiser Doctrine

Cruiser Doctrine deals primarily with their 8” gunned ships assigned to Second Fleet. Light cruisers were generally assigned to destroyer, and in rare cases submarine, squadrons as flagships. The focus here is on traditional cruiser duties, not their new duties in “carrier warfare” which is dealt with in the section on Diversion Attack Force Doctrine or in night fighting which is in the section on that subject. At the beginning of the war the Japanese had eighteen heavy cruisers organized into five divisions (4X4; 1X2) numbered 4-6. One division (Crudiv 6 aka 6S) was assigned to First Fleet (the battleship force) with the balance forming the core of Second Fleet, whose functions were those traditional to cruisers; scout and flank guard. In that role the tactical designation was Advance Force (Zenshin Butai).

During 1942-3 four ships were lost: KAKO, FURUTAKA, KINUGASA and MIKUMA. At the same time because of several reorganizations ships were moved around.

Tactics: The basic evolution unit is the Cruiser Division (usually 8” gun ships) designated by the Roman letter/Arabic number combination which corresponds with its division

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number; i.e. 4S=Cruiser Division 4.11 Standard distance for cruisers is 800m. Speed signals with acceleration tables for heavy cruisers are as follows:

Speed Standard 12k

14k 16k 18k Full

20-22kBS1*

24-26kBS2

28-30kBS3

31-32kBS4

33kBS5

Time required toaccelerate from one speed to thenext: min-sec

1-0 1-0 1-0 2-30

2-30 2-30 2-30 3-0 4-30

Total elapsed time

1-0 2-0 3-0 5-30

8-0 10-30 13-0 16-0 20-0

*BS=Battle Speed

General Doctrine: The standard cruiser division combat formation is the single column with the flagship in the lead though a fine quarter line may be used.

Cruisers are to provide covering gunfire for destroyers in torpedo attacks and when enemy battleships or cruisers are present launch their own torpedoes against those major units. They are to use their guns only against enemy light forces, though the use of torpedoes against enemy light cruisers and destroyers is not prohibited if the tactical situation indicates it is proper.

Day Action: The types of Day Action are:

Type Action

Outline of Action

Day Action I

A combination of all forces will close on the enemy swiftly and destroy him in one stroke

Day Action Ro

In drawing out the enemy, torpedoes will first be fired secretly from long range. Normally a swift pursuit by all forces will develop simultaneously with the arrival of the torpedoes at the target.

Day Action

A long range frontal engagement (Taijisen) will be undertaken at dusk with the object of precipitating a night action.

11 Technically this is 4S doctrine. By virtue of their assignment to Second Fleet (Diversion Attack Force) the other Second Fleet Cruisers were bound by it. Memo 13 of August 1943 sets this out: “Accordingly, all cruiser divisions . . . of the Imperial Navy will establish their doctrine . . . in accordance with the doctrine established by the Diversion Attack Force” (see chapter 8 for that memo).In 1944 there were three cruiser divisions assigned to Second Fleet: 4S (ATAGO, CHOKAI, MAYA, TAKAO), 5S (MYOKO, HAGURO) and 7S (SUZUYA, KUMANO, TONE, CHIKUMA). MOGAMI was a special duty ship assigned to Third Fleet. Cruiser divisions assigned to area fleets were: 14S NAKA, ISUZU(deactivated March 1944) 16S ASHIGARA to February 25; AOBA from February 25 to November 5, OI, KITAKAMI, KATORI, KINU. 21S NACHI, ASHIGARA (after February 25), TAMA, KISO.

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HaDay Action Ni

A test of strength will be avoided. A conclusive battle will be joined after the enemy has been drawn out by friendly forces.

Notes to Day Action:An engagement on same course will be called Method 1; opposite course Method 2. No special signal will be issued for Method 1.

The cruiser forces are responsible for screening the battle force and reporting enemy dispositions to facilitate the deployment of the battle force and exploiting torpedo opportunities. If the enemy battle line is observed deploying a large spread of torpedoes should be fired across the enemy line of advance to confuse or destroy the enemy battle line early in the action.12

Surface Gunnery: Night: Gunfire is to be opened at 18,000 meters when star shells are used for illumination while 10,000 meters is opening range when searchlights are used (12,000 meters in the South Seas).

Anti Aircraft Gunnery: Anti Aircraft cannon and heavy machine guns are to be used in surface engagements at the discretion of the ship’s captain. Standard opening ranges for anti aircraft weapons are:Cannons (12.7cm, 12 cm, 10 cm, 7.6 cm) 10,000 meters (day), 7,000 meters (night)Machine Guns (25mm, 13mm, 7.7mm) 3,500 meters

Torpedoes: The center ship in the enemy’s lead battleship division is the point of aim for torpedo attacks. When an enemy division contains two or four units the number two ship will be chosen as point of aim. Torpedoes will be set at 6 meters depth for battleships and large carriers; 5 meters for heavy cruisers and medium carriers; while 3-4 meters will be used against mixed formations. The optimum ranges for firing torpedoes is considered 5 kilometers (3 miles). This, of course, applies to standard attacks. Generally #2 torpedo speed (36 knots) will be used for day or night fighting though division or ship commanders may make appropriate speed changes depending on the tactical situation. Concentrated salvos or spread salvos may be used depending on the tactical situation.

Single line ahead or a quarter line (line of bearing) of less than 30 degrees are the preferred torpedo firing formations. In quarter line care is to be taken to avoid torpedoes of ships ahead in the formation.

The type 93 torpedo allows cruisers to conduct Long Range Concealed Attacks. Air spotting and lookout information is to be used to insure adequate information for long range attacks. Spare torpedoes from the disengaged side are to be used as first reloads thus giving the tubes on the engaged side three shots per tube. Torpedoes are to be used liberally. In the advanced phases of a battle, the practice will be to approach as close to

12 For comparisons see USF 20 CURRENT TACTICAL ORDERS CRUISERS, US FLEET, USF 21 CURRENT DOCTRINE CRUISERS US FLEET and, for the Royal Navy, THE FIGHTING INSTRUCTIONS, 1939. The latter can be found on line at the HMS HOOD ASSOCIATION

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the enemy as possible and to fire continuously at short range without giving the enemy a chance to evade the attack. In all cases, however continuous firing will be by special orders.

In Night Long Range Concealed Attacks firing will be at the limit of the field of vision and all aids to fire control will be exploited (star shells, parachute flares, aircraft dropped float flares, radio direction finders and radar) so firing beyond the field of vision can be accomplished. Ideally concealed attacks will be timed so the torpedoes arrive at the time night attacking destroyers arrive at their firing position. In carrying out concealed joint torpedo actions from both flanks of the enemy main force while in separate contact with both quarters of the enemy, the time of firing will be designated and normally the basic course and speed of the enemy will be given by order. In order to make firing at the designated time possible, each ship will proceed toward the enemy and make timely position reports. All ships will maintain close liaison, get on the target and fire at the time designated. The angle of fire will be selected to cover the direct advance or a 40 degree evasive turn by the enemy. Concealed firing carried out in cooperation with friendly cruiser division(s) in contact on the opposite flank will follow an outline set forth above.

Aircraft: Cruisers (and battleship) based aircraft are tactically assigned to the Cruiser Division Commander while they are the administrative responsibility of the individual ship. In operations the aircraft on the windward catapult will be launched first. Unless otherwise ordered aircraft will return to their ship upon completion of their mission, conducting a short ASW search before recovery. In special cases they might be put ashore at a friendly base after their mission is completed.

The functions of cruiser floatplanes are as follows:

Type Primary Functions Secondary FunctionsThree SeatAircraft*

Search, Tracking, Reconnaissance Attack, Anti Submarine, Anti Aircraft patrol

Two SeatAircraft*

Anti Submarine, Anti aircraft patrol, gunnery and torpedo observation, search,Reconnaissance.

Attack

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Notes: Other functions will be performed depending on the battle situation and other considerations.

*In 1944 the aircraft types assigned to Second Fleet Cruisers were E13A “Jake” (3 seat) and F1M “Pete” (two seat).

13 Cruiser (and to a lesser extent battleship) floatplanes played a vital role in long range reconnaissance for the Japanese Navy. As completed the TONE class ships had enhanced aircraft handling facilities to fulfill this role. In fact they were designated as scouting cruiser (sakuteki junyokan) or aircraft cruiser (koku junyokan). Cruiser MOGAMI was modified (after damage received in the Battle of Midway) to aircraft cruiser standards.

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To get a full picture of Japanese cruiser doctrine from the NACHI documents Combined Fleet Doctrine, Night Operations Doctrine and Diversion Attack Force Doctrine must be read in conjunction with this paper.

The greatest difference between Japanese cruiser doctrine and that of the U.S. Navy and Royal Navy is in the area of night fighting. The substantial difference can be summed up in this quote from the Royal Navy’s Fighting Instructions; “’Stationing of 8 inch Cruisers at Night’. The employment of 8 inch cruisers at night is a difficult problem. They are important ships whose armament is not specially suited for dealing with light craft at night, and they are large and unhandy targets vulnerable to both gun and torpedo. If sufficient screening forces are available without them, the 8 inch cruisers should normally be stationed in the line of the heavy ships. If, however the fleet is short of screening forces, the 8 inch cruisers may be stationed in pairs on the quarter of the battle fleet since they can generally move out counter attack without the necessity for large alterations of course.” The reason for this wide variance can be explained in one word: torpedoes. While the USN and RN were offloading torpedoes from their 8 inch gunned cruisers at the same time the IJN was enhancing the torpedo armament of theirs. The torpedo armament of Japanese cruisers by the beginning of the war was huge: MYOKO and TAKAO classes 16x24” tubes and 8 reloads. MOGAMI and TONE classes 12x24” tubes and 12 reloads. All were capable of firing the type 93 long range torpedo. The Japanese considered these ships capital ship killers.

11 Communications Lessons (March 1943) Battle of Attu (Komandorski)

This is a document produced by Fifth Fleet Headquarters dated 25 April 1943. In translation it is over 30 pages in length.

It is divided into six sections and fairly rich in detail.

Battle Lessons, Observations and Outline of Progress of Communications in Battle off Attu (Komandorski)

A. Division of Forces. (table of organization; nothing unseen in any number of sources)

B. Communication Plan for the operation: Unfortunately some of the materials are difficult to read but there is some fleet broadcast information including frequencies and broadcast stations: Ominato and Paramushino.

C. Outline of Communications control and progress of Communications: very detailed section covers frequencies guarded and a discussion of damage to NACHI. At 0350 received hit at base of main mast and enumerating various antenna etc effected. Other ships omitted.

D. Interception of enemy communications. This is fascinating. It is essentially a log of interceptions of USN transmissions with US frequencies, call signs (including international and encoded, the latter by recognition of operator’s “hand” etc.) and

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traffic analysis. This consists of a log/table of intercepted transmissions; time and frequency, call signs of originator and addressee(s), number of code groups and analysis. This includes USN ships, shore bases and aircraft. The following is a summary of US ships communications: Total interceptions 14 ships with nine call signs used by “Pensacola” class ship listed. Since they had the SALT LAKE CITY’s international call sign I assume that referring to the ship as “Pensacola” class was a formality. Analysis of “Operational Urgent” transmissions; 20 approximate; US frequency used for those 4165 kw (8339). Highest ranking US officer probably at Dutch Harbor. US Aircraft communications analyzed using same format with wave length, aircraft call signs, etc. US Army aircraft frequencies.

E. Damage and Damage control. Drawing of NACHI main mast area showing Antenna, location of radio rooms, hit and damage. Detailed outline of radios and location as well as damage received.

F. Battle Lessons: 10 pages of detailed analysis.

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