AU/ACSC/STUDENT#-4577/2004-05

AIR COMMAND AND STAFF COLLEGE

AIR UNIVERSITY

LESSONS FORGOTTEN: ROYAL NAVY ANTI-SUBMARINE

TACTICS OF WORLD WAR I

by

Darin C. Curtis, LCDR, USN

A Research Report Submitted to the Faculty

In Partial Fulfillment of the Graduation Requirements

Instructor: Lt Col Matthew C. Stafford

Maxwell Air Force Base, Alabama

April 2005

Distribution A: Approved for Public Release; Distribution is Unlimited

Disclaimer

The views expressed in this academic research paper are those of the author and do

not reflect the official policy or position of the US government or the Department of

Defense. In accordance with Air Force Instruction 51-303, it is not copyrighted, but is

the property of the United States government.

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Table of Contents

Page

DISCLAIMER ....................................................................................................................ii

PREFACE......................................................................................................................... i v

ABSTRACT...................................................................................................................... vi

CHAPTER 1 INTRODUCTION .........................................................................................1

CHAPTER 2 GERMAN U-BOAT CAMPAIGN IN THE EARLY STAGES OF WWI...............................................................................................................................3

CHAPTER 3 BRITISH ANTI-SUBMARINE EFFORTS, AUGUST 1914-APRIL 1917...................................................................................................................6

CHAPTER 4 THE EVOLUTION OF BRITISH ANTI-SUBMARINE WARFARE, 1917 - 1918...............................................................................................9

CHAPTER 5 THE ROYAL NAVAL AIR SERVICE IN THE ANTI-SUBMARINE WAR....................................................................................................14

CHAPTER 6 ROYAL NAVAL AIR SERVICE FIXED-WING ANTI-SUBMARINE WARFARE .........................................................................................16

CHAPTER 7 THE IMPACT OF THE FLYING BOATS ON THE CONVOY SYSTEM......................................................................................................................19

CHAPTER 8 UNITED STATES NAVY ANTI-SUBMARINE WARFARE PRE 1999..............................................................................................................................22

CHAPTER 9 DEGRADING ANTI-SUBMARINE CAPABILITIES WITH THE DEMISE OF THE U.S.S.R..........................................................................................27

CHAPTER 10 GATHERING THREATS.........................................................................31

CHAPTER 11 CONCLUSION..........................................................................................34

BIBLIOGRAPHY..............................................................................................................37

iii

Preface

In the process of deciding on an appropriate subject for this research paper, I

wanted to address a particular concern shared by many officers in the United States

Navy’s S-3B Viking community. The S-3B “War Hoovers,” as they are known by their

aircrews, were the only fixed-wing anti-submarine warfare (ASW) aircraft organically

based on the Navy’s aircraft carriers. The Viking community is currently in the process

of decommissioning all ten operational squadrons. No comparable ASW asset is on the

drawing board to replace the S-3B. The decision to retire the Vikings was a result of the

demise of the Soviet Union and the ending of the Cold War. It is my contention that the

act of degrading our ASW capabilities in the face of increasing submarine threats from

China, North Korea and Iran could prove disastrous.

To argue my point on this matter, I have chosen historical lessons learned from

the British Royal Navy of World War I in its struggle to address the threat of the German

U-boat campaigns. Current strategies and tactics for fighting submarines with air power

had their roots in the actions of the Royal Naval Air Service (RNAS). The technologies

used by ASW aircraft today were envisioned and introduced in World War I. Finally, air

power played a significant role in the defeat of the U-boats as will be demonstrated in the

course of the paper. The parallels between RNAS tactics and current ASW tactics are

numerous and it is apparent to modern day sub hunters that the lessons learned from the

RNAS are being forgotten at our peril.

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The majority of the historical data is gleaned from Paul Halpern’s book, A Naval

History of World War I. His descriptions of the submarine campaigns undertaken by the

German Navy and British attempts to find a viable defense proved very enlightening.

Furthermore, Squadron Leader T. D. Hallam’s The Spider Web, The Romance of a

Flying-Boat Flight in the First World War, gave aircrew descriptions and insight into the

first use of air power in ASW campaigns. His descriptions of search tactics, attack

profiles and the integration of ASW technologies with the airplane depict the roots of

current ASW doctrine. Finally, statistical figures from World War I were directly lifted

from “The World War I Document Archive,” an on-line collection of historical data

compiled by World War I historians. An examination of lost shipping data from this

archive underscores the impact of air power on submarine success.

It is therefore my view that, from a historical perspective, the United States Navy

is blindly “painting itself into a corner” by divesting itself of significant ASW

capabilities. It is hoped that this work may serve to remind others of the lessons learned

in anti-submarine warfare.

v

Abstract

The United States Navy is currently divesting itself of a significant portion of its

airborne anti-submarine warfare (ASW) capability on its aircraft carriers. The decision to

retire the S-3B Viking creates a critical vulnerability that is exploitable by China, North

Korea and Iran as they aggressively invest in their respective submarine capabilities.

World War I offers a unique opportunity to compare the effectiveness of waging

war against submarines both with, and without the integration of air power. During the

first two and a half years of the conflict, ASW was waged by the British Royal Navy

(RN) without the use of aircraft. Significant improvement in ASW followed the

introduction of air power during the final 18 months.

The World War I parallel applies to the modern era, except in reverse order. The

United States Navy combined the most modern technologies, tactics, techniques and

procedures for ASW warfare in one carrier-based asset, the S-3B. The Vikings were in

effect, the personification of every ASW lesson learned by the British in the Great War.

For three decades, the Vikings proved themselves to be highly effective Cold Warriors

against Soviet submarines. With the fall of the Soviet Union, they were quickly slated

for retirement. The first of ten operational squadrons decommissioned in April, 2004.

In the interest of trimming military expenditures, the United States Navy has willfully

degraded the ability of its aircraft carrier strike groups to conduct ASW missions. The

limitations imposed by this decision represent a defensive weakness in the carrier strike

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groups readily exploited by the previously named countries. The United States Navy, at

its own peril, is forgetting the ASW lessons learned in World War I.

vii

LESSONS FORGOTTEN: ROYAL NAVY ANTI-

SUBMARINE TACTICS OF WORLD WAR I

Introduction

The German Navy of World War I introduced the submarine to the world as a

highly effective weapon capable of bringing a nation to its knees. From 1914 to 1918,

the U-boats inflicted heavy losses on allied shipping and very nearly defeated Great

Britain.1 The Royal Navy struggled for two and a half years to devise an effective

strategy to defeat the German U-boats. In near desperation from heavy shipping losses in

1917, the British Admiralty, previously resistant to escorted merchant convoys,

authorized their use. Also in 1917, the Royal Navy began to employ air power as an anti-

submarine weapon. Flying boats, operating on a “Spider Web” search grid over the

North Sea, demonstrated formidable submarine hunting potential. The subsequent

integration of sea planes with the merchant convoy system proved to be the ultimate

weapon against the German U-boats.

The effectiveness of air power against the submarine was not lost on the United

States Navy for the remainder of the twentieth century. As a counter to the submarine

threat posed by the Soviet Union, the United States Navy developed the carrier-based S-

3B Viking, a fixed-wing jet aircraft. Designed from the beginning as a submarine hunter,

the Viking incorporated acoustic, electronic, magnetic and infrared technologies to

detect, locate, and track enemy submarines. The ability to carry four anti-submarine

1

torpedoes provided battle group commanders the flexibility to use the Vikings both to

detect and engage enemy submarines.

The demise of the Soviet Union initiated calls for budget cuts in US Naval

expenditures. These cuts ultimately led to the retirement of the Vikings and a reduction

in anti-submarine capability in carrier strike groups. The purpose of this paper is to draw

parallels between the lessons learned during the World War I submarine threat to Great

Britain and the gathering threats posed to the United States Navy by aggressive

submarine programs underway in China, North Korea, and Iran. The decision to reduce

anti-submarine warfare capability in the face of an expanding submarine threat may

ultimately prove contrary to the best interests of the United States. Arguably the

important lessons learned by the Royal Navy in World War I are being forgotten.

Notes

1 Paul G. Halpern, A Naval History of World War I (Annapolis, MD.: Naval Institute Press, 1994 341

2

Chapter 2

German U-boat Campaign in the Early Stages of WWI

In order to fully understand the evolution of ASW tactics practiced by the Royal

Navy during the course of the Great War, it becomes necessary to understand the U-boat

campaign undertaken by the German Navy. The first few months of the war were

marked by a haphazard effort by the German Navy to define its maritime strategy with

respect to the U-boat. Indeed, the first merchant taken by a German submarine, the

British steamer Glitra, was not taken until October 20, 1914, nearly three months after

the commencement of hostilities.1 The German strategy could best be described as

undefined and unfocused with offensive submarine doctrine yet to be developed.

Eventually realizing the potential of the U-boat as an economic weapon of

blockade, Germany finally settled on a submarine strategy and officially declared

unrestricted submarine warfare in early February 1915.2 Unrestricted submarine warfare

marked the German intent to sink without warning any vessels found operating in

specified waters. The blockade targeted all waters surrounding Great Britain and Ireland

with a specific focus on military shipping in the English Channel. At the commencement

of this campaign, Germany averaged six U-boats at sea per day from a pool of 37

completed vessels.3 This initial campaign against merchant shipping would last until the

following September when Germany succumbed to the political pressure resultant from

3

the sinking of neutral shipping. The sinkings of vessels from various non-belligerent

nations including the United States served to shape world opinion against Germany. Of

particular interest to the Kaiser at that time was keeping the industrial might of the United

States out of the war.

This first unrestricted campaign had devastating effects on British and Allied

shipping. By September, Germany had sunk in excess of 1,294,000 tons of shipping with

a 20:1 ship-to-U-boat kill ratio.4 Germany, for its part, lost ten U-boats, primarily to

armed British merchants known as Q-ships.5

The year 1916 marked a shift in German submarine strategy from one of

unrestricted warfare to one which operated under prize rules. Under prize rules, U-boats

approached target vessels on the surface, demanded their surrender and allowed the crew

and passengers time to abandon ship prior to the attack. Attacks were limited to Allied

cargo ships while attacks on passenger vessels and neutral vessels were to be avoided.

Although not as successful as the unrestricted campaign, Germany still sank over 500,000

tons of allied shipping during the first six months of 1916.6 Tonnage figures began to

climb in the second half of 1916 and into the first two months of 1917 with the Allies

averaging a monthly loss of 325,000 tons while Germany enjoyed a merchant vessel-to-

u-boat kill ratio of 65:1.7

Despite an expressed intent to only attack the vessels of hostile nations, Germany

inadvertently attacked some neutral shipping and became the subject of international

criticism. Sensing the need to hasten the defeat of Great Britain, the German Admiralty

sought and obtained the Kaiser’s blessing to resume unrestricted submarine warfare in

February 1917. British losses quickly climbed to an average of over 600,000 tons per

4

month with April of 1917 marking the high point in the German U-boat campaign with

860,334 tons destroyed. By the end of June 1917, German submarines enjoyed a 167:1

kill ratio against enemy shipping.8 The British Admiralty knew that these kinds of losses

were unsustainable and subsequently began to consider different techniques in anti-

submarine warfare.

Notes

1 Ibid. 292 2 Ibid. 293 3 Ibid. 294 4 Ibid. 294 5 Ibid. 294 6 Ibid. 308 7 Ibid. 335 8 Ibid. 341

5

Chapter 3

British Anti-Submarine Efforts, August 1914-April 1917

The British Admiralty struggled to define the best tactics to counter the U-boat

threat. An “offensive” strategy that actively hunted down and destroyed the U-boats was

sought from the first days of the war. The specific techniques adopted in an attempt to

accomplish this were more an effort at trial and error. The tactics that eventually

defeated the U-boats would not be adopted until 1917.

Initially, the British utilized a fleet of converted civilian schooners known as the

Auxiliary Patrol to “sanitize” the sea in the immediate coastal areas surrounding port

cities. This force of small craft was charged with seeking out and attacking German

submarines. The main detection method employed by the Auxiliary Patrol was visual

sighting. Their numbers were too small however, and the amount of sea space that

needed patrolling too great, for the Auxiliary Patrol to be very effective.

Another strategy, albeit more defensive in nature, was the establishment of

minefield barriers in the Dover Straights and in the northern channel of the Irish Sea.

The idea behind this strategy was to deny the U-boats operational sea space and to protect

vital British choke points. This approach however, also failed to produce satisfactory

results as the Royal Navy was plagued throughout the war by defective mines and mines

6

breaking loose from their moorings. Ultimately, the minefields proved nothing more than

a nuisance for German submarines.

An interesting offensive tactic involved British trawlers putting to sea in known

U-boat operational areas, with a British submarine in tow. Using this tactic, the British

sub could remain submerged while conserving its batteries and when a German

submarine approached the trawler, on the surface, a message would be sent by connecting

telephone line to the British sub and a submarine-on-submarine engagement could

commence. While an interesting and creative approach, German U-boats soon became

wary of the trawlers and U-boat losses were negligible.

Perhaps the most effective British weapon against the U-boat in the first few years

of the war was the “Q-ship.” These were merchant ships intended to deceive U-boat

skippers by utilizing hidden arms and a second, specifically trained crew. The U-boat

would approach the Q-ship, demand its surrender, and watch while the first “crew”

abandoned ship. While the first crew was abandoning ship, the second crew would

unveil the Q-ship’s guns and open fire on the U-boat. The majority of the ten U-boats

lost during the first unrestricted submarine campaign were lost to Q-ship tactics although

the U-boats still enjoyed a 20:1 kill ratio.1

Of note in these early years of anti-submarine warfare was the Admiralty’s

reluctance to utilize convoy tactics. The concept was rejected as being too “defensive,”

in nature because it sought to avoid submarines. It was thought that the only honorable

occupation of naval officers in a maritime engagement was in the active pursuit and

attack of hostile vessels.2 Mounting merchant losses however, would eventually force the

Admiralty to reconsider the use of convoy tactics. Ultimately, the convoy system would

7

curtail merchant losses and prove to be the best line of defense against the U-boats.

Furthermore, in the last year and a half of the war, the use of aircraft would render the

convoy system virtually immune to submarine attacks.

Notes

1 Ibid. 296 2 Ibid. 351

8

Chapter 4

The Evolution of British Anti-Submarine Warfare, 1917 - 1918

At the pinnacle of U-boat success in April 1917, it became apparent that the

British approach to anti-submarine warfare (ASW) was largely ineffective. Mounting

losses demanded a change in strategy and spurred a philosophical shift in Royal Naval

(RN) ASW doctrine from an “offensive” nature to a “defensive” one. The strategy of

attempting to offensively cleanse water space for the safe passage of merchant vessels

was replaced by one that would seek to defend the vessels themselves while in dangerous

waters. Instead of attempting to actively detect, fix and destroy submarines, the focus

shifted to denying submarines the opportunity to track and destroy targets. The concept

that a submarine could be rendered ineffective by mission denial began to take root in the

RN. The new mindset spawned several new technologies and strategies designed to

harass U-boat commanders and to decrease their attack capabilities.

From the war’s inception, the British had been exploring new technologies in the

form of acoustic submarine detection. This led to the development of hydrophones,

which are essentially submerged microphones. Hydrophone stations were established at

vital choke points along the British coast and smaller hydrophones were deployable from

surface vessels. The use of hydrophones, however, merely alerted the British of a

submarine’s presence; they were not capable of actually locating a U-boat. By 1917

9

however, the technology began to integrate itself with other ASW strategies. The ability

to acoustically detect a submerged submarine allowed British commanders to employ

other assets to keep the submarine submerged. This forced the U-boats to deplete battery

power and prevented them from acquiring a firing solution on surface targets. Although

not “killed,” the U-boats were made ineffective through mission denial.

In addition to new acoustic technology, Great Britain sought to further reduce U-

boat effectiveness by laying minefields in the vicinity of German naval bases.1 These

minefields were secretly placed by British submarines. This concept reduced U-boat

effectiveness by forcing German crews to consume more time and fuel while navigating

mined waters. The desired end result of this harassment was a shorter operational patrol

time and theoretically, fewer merchant losses. Coincidentally, the strategy was

responsible for the sinking of seven U-boats between August and December, 1917.2

The spring of 1917 also marked the beginning of another U-boat harassment

strategy. The British began implementing significant sea barriers referred to as barrages.

A barrage is a sea barrier that combines the use of metallic mine “nets” hung from

floating barriers coupled with deeply moored mines below the nets. By 1918 the barrage

nets also included electronic contact mines embedded within the netting itself.3 The

intended effect was to create an undersea wall to discourage U-boat passage. Initially,

barrages were used on a small scale to protect port entrances, but the idea was expanded

to protect sea lane choke points. The first significant barrage was established off the

Belgian coast and eventually extended to the Dover Straights. These waters were

patrolled by destroyers and other small surface vessels in an attempt to force the U-boats

to submerge for passage, essentially herding them into the barrages. From January to

10

November, 1917, only one U-boat was documented to have been sunk as a result of these

barrages while 253 conducted safe passage.4 To counter this British strategy, the U-boats

simply slipped over the barrage on the surface while under the cover of darkness. Great

Britain responded further with the use of light vessels which used powerful spotlights at

various points across the channel in an attempt to force the U-boats to submerge for

passage. The addition of these vessels resulted in 14 U-boat sinkings on the Dover

barrage during 1918.5 Although not impenetrable to U-boat passage, the barrages

undoubtedly harassed the U-boats and contributed to the safe passage of untold numbers

of merchant vessels. The Dover barrage proved to be a vital factor in reducing U-boat

effectiveness and in maintaining logistic supply lines between the English and French

coasts.

Ironically, at the height of the successful U-boat campaign in April 1917, the RN

begrudgingly initiated a large convoy system for colliers traveling from Britain to

France.6 Previously, only small convoys had been used to make the “beef” runs between

the Flemish coast and England. Convoys had been resisted to this point under the belief

that they only massed merchant shipping into large, easily targeted formations which

would ultimately only simplify the mission of U-boat commanders. The convoy concept

was further resisted due to perceived congestion in port facilities both at the point of

embarkation and debarkation. With all vessels either arriving or departing

simultaneously, seaports would be swamped with cargoes and the resultant inefficiencies

would hamper the war effort. Finally, a convoy would be limited to the speed of its

slowest ship which would create longer passage times and expose the shipping to

11

prolonged periods in dangerous waters. The 860,000 tons of shipping sunk in April 1917

forced the Admiralty to test the larger convoy system.

The convoy approach consisted of a simple strategy of combining multiple

merchant ships under the protection of destroyers and cruisers for a single passage

through U-boat patrolled waters. Convoys proceeded along approved routes with specific

sail times and typically left port at dusk while timing their arrival at dawn to take

maximum advantage of darkness. The convoys also incorporated zigzaging which

complicated a submarine’s firing solution and reduced its effectiveness.

The British Admiralty was astonished at the results of the trial convoy system

between Great Britain and France. From March to May, 1917, the British sailed 4,016

individual ship sorties under protected convoy and lost only nine ships to U-boats for a

0.22% loss rate.7 The results were encouraging enough to institute the convoy system

through all waters patrolled by the U-boats. By the end of September, the figures for

tonnage lost were in a steep decline and were effectively cut in half from a high of

860,000 tons in April to 354,000 by October. Furthermore, the merchant-to-U-boat kill

ratio dropped from 167:1 in April to 16:1 by September.8 It should be noted, that the

convoy system achieved this success not by killing U-boats, but by rendering them less

effective.

The German response to the convoy system in 1918 was to put more U-boats to

sea and to concentrate production on newer and longer-ranged classes which could

conduct extended operations at sea. While still able to inflict some losses on Allied

shipping, the Germans were never able to repeat the success they enjoyed in early 1917.

Throughout 1918, the U-boats averaged around 240,000 tons sunk per month and were

12

never able to push the monthly tallies over 400,000.9 The kill ratio also held steady at

16:1 through the final months of the war. The convoy system proved to be a decisive

measure in defeating the U-boat campaigns; however, the convoys were made even more

effective with the introduction of air power in the ASW fight.

Notes

1 Ibid. 344 2 Ibid. 345 3 Ibid. 350 4 Ibid. 350 5 Ibid. 408 6 Ibid. 351 7 Ibid. 365 8 Ibid. 365 9 Ibid. 423

13

Chapter 5

The Royal Naval Air Service in the Anti-Submarine War

The Royal Naval Air Service (RNAS) began to integrate the use of air power in

the form of kite balloons and lighter-than-air ships during the U-boat campaigns of 1915-

16. The kite balloons were trailed behind combatant vessels and essentially served as

extended “crows nests” for the purpose of sighting enemy submarines or surface

combatants at greater distances. Lighter-than-air ships patrolled the waters in

conjunction with surface vessels. The earlier detection provided the battle group

additional time to maneuver into an optimal position to keep a U-boat submerged. While

submerged, a U-boat was slow and effectively prevented from closing target vessels and

acquiring a torpedo firing solution.

Despite their obvious benefits, the kite balloons and air ships also imposed upon

the British a singular disadvantage; while aiding in the location of enemy vessels, they

also revealed the position of the British surface combatants.1 German U-boats, by 1916,

had incorporated the use of altitude lenses on their periscopes thus enabling them to sight

British aircraft as well as surface vessels.2

For the purposes of this discussion, both types of aircraft were slow moving and

neither contained any offensive capabilities against either surface vessels or U-boats.

Their main advantage was in enemy detection, but that detection went both ways. In a

14

sense, their use resulted in a tactical draw. The subject is addressed here to make the

point that although the initial use of kite balloons and lighter-than-air ships pre-dated the

British strategy of U-boat mission denial; it provided the RN with an early glimpse of the

advantages gained by reducing U-boat mission effectiveness.

Notes

1 Ibid. 424 2 Squadron Leader T. D. Hallam, The Spider Web, The Romance of a Flying-Boat

Flight in the First World War (London-Melbourne: Arms and Armour Press, 1979) 59

15

Chapter 6

Royal Naval Air Service Fixed-Wing Anti-Submarine Warfare

The conceptual use of fixed-wing aircraft as a weapons platform against the U-

boats was envisioned from the first U-boat campaigns. RNAS sea planes were initially

designed and built specifically for submarine hunting, reconnaissance and air-to-air

combat with German sea planes.1 Suitable “flying boats”, as the sea planes were called

by their crews, did not appear in adequate numbers until the spring of 1917 due to several

factors. The British prioritized the building of airplanes for use by the army while the

RNAS concentrated on airplanes that could be launched from surface vessels, a

technology that surface craft would not possess until later in the war. The first flying

boat squadrons were established at Felixstowe Naval Air Station on the Southeastern

coast of England in the spring of 1917.2 From Felixstowe, and later from other naval air

stations, the “Spider Web” anti-submarine campaign was launched.

German submarines, returning from patrol in the straits of Dover or from the

North Sea, were forced around the Hook of Holland and into the more restricted waters of

the Helgoland Bight as they transited to their home ports. As part of German standard

operating procedure, the U-boats announced their return by wireless communications.

Unknown to the Germans, the British had established two wireless direction-finding

stations on the English coast which could pick up German transmissions, plot a bearing

16

from each particular station, and roughly determine the U-boats’ position based on

wireless cross fixing.3 The RN discovered that the majority of these U-boat fixes fell in

the vicinity of a Dutch light vessel, essentially a floating and stationary light house

known as the North Hinder light vessel.4 With this discovery, the RNAS flying boat

squadrons designed a circular-shaped search grid centered on the North Hinder light

vessel. That grid became known as the Spider Web. It had eight radial arms extending

30 nautical miles with concentric rings at 10, 20 and 30 miles. The grid encompassed

4,000 square miles and a single flying boat was capable of searching a one-eighth pie-

shaped portion on a typical sortie.5 When a U-boat broke radio silence to announce its

return, a wireless cross fix was generated and a flying boat was launched to that particular

portion of the spider web to find and attack the submarine.

Flying boats initially carried four 100 pound, (later 230), bombs each with two-

second delayed fuzing to allow for water penetration up to 60 feet before exploding,

hopefully in the vicinity of the submarine.6 Typical attack runs on the submarines were

conducted at 600-800 feet in a level flight configuration flying up the wake toward the

stern of the surfaced U-boat at speeds between 60 and 80 knots.7

In the first month that the Spider Web was employed, the flying boats sighted

seven U-boats and attacked five.8 During the entire Spider Web campaign, spanning the

rest of the war, 40 flying boats sighted 68 U-boats and bombed 44.9 The campaign was

particularly effective in the final six months when there were 26 sightings and 18

attacks.10

The Spider Web campaign conducted by the flying boats of the RNAS succeeded

in harassing and destroying enemy submarines from April 1917 through October 1918.

17

While it is impossible to determine just how much of an impact the campaign had on

German operations and subsequent Allied sinkings, the fact remains that the airplane was

proving itself to be a formidable anti-submarine platform. Some of the search-and-attack

tactics devised and implemented on the Spider Web are practiced by navies around the

world today. The greatest impact of the fixed-wing aircraft in the RNAS during World

War I, however, was realized in support of the convoy system.

Notes

1 Ibid. 2 2 Ibid. 8 3 Ibid. 32 4 Ibid. 32 5 Ibid. 33 6 Ibid. 40 7 Ibid. 40 8 Ibid. 78 9 Ibid. 242 10 Halpern, 441

18

Chapter 7

The Impact of the Flying Boats on the Convoy System

With the increasing effectiveness of the barrage in the Dover Straights in the last

18 months of the war, the flying boat squadrons in Southeastern England began to

discover fewer targets in the waters covered by the Spider Web. To keep flying skills

sharpened, the RNAS began integrating the flying boats into the convoy system.

Initially, coordination between destroyers, cruisers and flying boats was difficult as there

were no procedures for integrating aircraft into convoy operations. The U-boats, it was

discovered, typically conducted torpedo attacks on single merchant ships from a range of

300-600 yards while submerged in front of their prey. To attack a convoy, however, the

U-boats positioned themselves 500-1000 yards in front of the convoy and shot a torpedo

not at a particular ship, but at the cluster of vessels.1 Critical to the success of a torpedo

attack, was the U-boat’s ability to place itself in front of the convoy. To accomplish this,

a U-boat had to surface to discover the convoy in the first place, determine its course and

speed, and then position itself in an optimal firing position. The weakness of having to

surface to determine the location of a convoy was exploited with great effectiveness by

the flying boats.

The day prior to the departure of an escorted convoy, flying boats were assigned

to patrol the intended route in order to “cleanse” it of enemy submarines. This had the

19

effect of driving the U-boats to submerge and denied them the opportunity to charge their

batteries in anticipation of an attack. The following day, when the convoy sortied, flying

boats continued to patrol the waters ten nautical miles in front of the convoy. This

further limited a U-boat’s ability to maneuver to a perfect firing position as again, it was

forced to submerge, cutting its speed in half and rapidly depleting its batteries.2 The

flying boats were limited to three hours on station so several shifts were flown to provide

unbroken air cover along the entire route through dangerous waters.

Once the Royal Navy finally settled upon a convoy strategy, and combined it with

the technologies and other supporting strategies previously discussed, the effectiveness of

the U-boat steadily degraded. From April, 1917 through October 1918, the British

provided escort protection for 83,958 individual ship sorties in all operational waters.

From those sorties, 257 ships were sunk due to U-boat attack for a loss rate of only

0.31%.3 The convoy system had proven to be very effective at removing the

effectiveness of the U-boats without actually destroying them in significant numbers. Of

even greater interest however, is the effectiveness of the flying boats in support of the

convoy system. Within the numerous convoys that were escorted by surface combatants

in combination with flying boat assets, a grand total of only two ships were lost during

the entire period of their employment.4

The contributions of RNAS fixed-wing aircraft to the ASW campaign of World

War I are difficult to quantify. While several “sightings” and “attacks” were made by the

flying boats operating on the Spider Web, the actual number of “kills” made by aircraft

remains unknown. What is certain is that the airplane was very effective at harassing the

U-boats and forcing them to submerge, thereby limiting their capabilities. Aircraft-

20

protected convoys were virtually immune to U-boat attack.5 The lessons learned and the

capabilities demonstrated by the RNAS in the U-boat campaigns of World War I

provided a foundation for airborne anti-submarine warfare which would last into the

twenty-first century.

The Royal Navy combined several capabilities to detect, localize, track, and

defeat German submarines. No single tactic or weapon single handedly defeated the U-

boats, but rather it was a combination of various techniques and evolving strategies.

Some strategies were quickly embraced, the armed Q-ship for example, while others were

resisted, like the convoy system. The Royal Navy combined the use of mine warfare,

barrages, hydrophones, wireless radio listening stations, Q-ships, zigzag course patterns,

escorted convoys, spider web surface search grids and airborne convoy escorts in an all-

out effort to defeat the U-boats. That victory was eventually gained, not by destroying

the German submarines, but by rendering them ineffective. The ASW tactics, techniques

and procedures practiced today trace their roots to the Royal Navy of World War I.

Notes

1 Hallam, 80 2 Ibid. 81 3 “The World War I Document Archive” August, 1995, on-line, Internet, available

from www.gwpda.org/naval/stats006.htm. 4 Ibid. 5 Halpern, 426

21

Chapter 8

United States Navy Anti-submarine Warfare Pre 1999

It should come as no surprise that the United States Navy and other navies of the

world have studied and incorporated the lessons learned from the Allied ASW campaign

of World War I. Like the Royal Navy from 1914-1918, the United States Navy does not

rely on any single tactic or platform, but rather combines multiple capabilities from

various assets in an integrated effort to detect, classify, track and possibly attack enemy

submarines. The height of this anti-submarine effort was reached during the Cold War

when submarines from the Soviet Union regularly patrolled every ocean of the world.

To detect the presence of submarines in the First World War, the Royal Navy

relied heavily on visual contact from surface craft, kite balloons, and aircraft. Eventually

the RN incorporated the use of acoustic technology in the form of crude hydrophones.

The electronic spectrum was also exploited through the use of wireless listening stations.

All these detection capabilities worked together to notify British commanders of enemy

submarine presence.

In addition to these specific detection techniques developed by the British, the

United States would adopt technologies which would incorporate space power. Space

power would be used to enhance visual detection in the form of satellite imagery of

submarine departures from Soviet Naval bases.

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Acoustic detection capabilities were greatly increased by improving upon the

British hydrophone model and placing hydrophones on submarines and surface

combatants in the form of bow-mounted sonar domes and towed-array sonar.

Furthermore, acoustic technology was developed for use by aircraft in the form of

sonobuoys and dipping sonar.1 Finally, combining the principles of a World War I

barrage and acoustic technology, permanent detection hydrophones were placed along

underwater “choke points” transited by Soviet submarines in the North Atlantic and

Pacific which alerted US Naval commanders of Soviet activity.

The use of the electronic spectrum to detect submarines was greatly enhanced by

improvements in electronic surveillance measures (ESM). Building upon the concept of

“wireless” listening outposts developed by the British, the US Navy placed ESM

equipment on surface ships, submarines and aircraft which are capable of working in

unison to triangulate an accurate “wireless” fix of an enemy submarine’s position.

Furthermore, the invention of Radio Detection and Ranging (RADAR), and specifically

Inverse Synthetic Aperture Radar (ISAR)2, greatly enhanced the use of the electronic

spectrum to detect submarines.

Even the earth’s magnetic field has been exploited for the purposes of submarine

detection, and more specifically, position fixation. Submarines create local anomalies in

the magnetic field as they transit the oceans. Naval aircraft have been equipped with

Magnetic Anomaly Detection (MAD) equipment which alerts aircrews to a submarine’s

presence when the aircraft flies directly over a submarine, thereby not only detecting it,

but accurately fixing its position.

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All of these technologies, exploiting the physics of the electronic, magnetic,

acoustic and visual spectrums have been incorporated, to the maximum extent possible,

by naval and national assets in the subsurface, surface, airborne and space mediums.

Working in unison, they have created formidable anti-submarine warfare capabilities.

The parallels between ASW practiced by the British in World War I and today’s

navies are not limited to the improvement and incorporation of ASW technologies. The

United States and Allied Navies have also revised and implemented World War I British

ASW tactics. Unable to actively hunt and destroy Soviet Submarines without sparking

World War III, the US Navy followed the British lead by devising tactics to minimize the

effectiveness of Soviet submarines. Although merchant convoy operations have not

been practiced by the United States since World War II, US Navy Carrier Battle Groups

and Amphibious Battle Groups, like the merchant convoys, were often followed by

Russian submarines during the Cold War. To minimize the impact of these submarines,

the US Navy employed surface craft, submarines and more specifically, aircraft to

cleanse the waters along the intended course of the respective battle groups. This had the

same effect on the Russian submarines that it had on the U-boats. Unable to approach

US battle groups to the desired range, Russian submarines could neither launch torpedoes

nor surface-to-surface anti-ship missiles. They were effectively defeated through mission

denial.

Current airborne ASW tactics trace their roots to the RNAS flying boat

squadrons. The generation of a rough submarine position based on wireless cross-fixing

resulted in the launching of a flying boat to the Spider Web search grid. Today, based on

submarine contact generated from any of the myriad of detection capabilities previously

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discussed, US Naval aircraft standing ASW alert launch to specific ocean search sectors

containing the suspected enemy submarine. Even airborne ASW attack principles follow

the standard established by the RN in World War I. Reminiscent of the flying boat

squadrons, US Naval aircraft, given the order, would attack an enemy submarine by

approaching from the stern, at low altitude, and dropping a torpedo on the submarines’

estimated position.

In the interest of developing platforms which build upon the World War I model,

and combine as much of this technology and tactical capability as possible, the United

States Navy developed and purchased the S-3B Viking carrier- based jet aircraft during

the 1960s and 1970s. Designed specifically as an anti-submarine asset, the Viking

combined acoustic technology in the form of sonobuoys, with MAD equipment, ISAR for

periscope detection, electronic surveillance equipment and infrared visual enhancement

all to detect and track Soviet submarines. In addition to all this detection capability,

these eyes in the sky also had teeth. The S-3B was capable of carrying up to four Mk-46

anti-submarine torpedoes. Finally, the S-3B, or “War Hoover” as she is known by her

crews, had the capability to remain airborne for up to seven hours without in-flight

refueling; a capability that allowed the searching of extensive amounts of water space.3

The combination of detection capabilities and firepower provided battle group

commanders a formidable ASW weapon in the S-3B Viking.

Notes

1 Dipping Sonar is a detection technique whereby a helicopter lowers a hydrophone while in a hover configuration. The hydrophone generates sonar contact with a submarine and can determine the range and bearing from the helicopter.

2 ISAR RADAR is a version of RADAR that can not only detect the presence of a ship, but is capable of classifying the type of ship and is especially adept at detecting a submarine periscope.

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Notes

3 Naval Aviation Training and Operations Procedures Standardization, S-3B Flight Manual, (San Diego, CA.: Naval Printing Office, 1998), Chap 2

26

Chapter 9

Degrading Anti-Submarine Capabilities with the Demise of the U.S.S.R.

With the fall of the Berlin Wall in 1989 and subsequent dissolution of the

U.S.S.R. the following year, the United States noted fewer and fewer submarine sorties

being conducted by the former Soviet submarine fleet. The United States Navy began to

find itself in the unfamiliar position of having to defend expenditures on ASW assets

against members of Congress who were clamoring for a “Peace Dividend.”

Near the end of the millennium, the US Navy began to trim its arsenal of fixed-

wing ASW assets by de-funding the ASW mission performed by its carrier-based

Vikings. Starting in 1997, the S-3B squadrons had their aircrews reduced in number by

25%. Furthermore, all acoustic computer hardware as well as software programs were

removed from the aircraft. Viking anti-submarine training ceased in both training and

operational squadrons.

Looking to gain additional cost savings, the US Navy decided to retire the S-3B

fleet altogether between the years 2004-2007. As of the writing of this paper, two of ten

Viking squadrons have already been decommissioned with an additional two set to retire

during 2005.

While the United States Navy still maintains its fleet of P-3C shore-based ASW

aircraft, it effectively stripped its carrier strike groups of their only fixed-wing, organic

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ASW asset. The ramifications of this decision are far reaching. The P-3C is an effective

submarine hunter, but is limited by shore-basing requirements and struggles to integrate

into carrier operations.

By retiring the Vikings, the US Navy carrier strike groups (CSG) no longer have

an on-board RADAR system designed to detect periscopes in waters beyond submarine

launched surface-to-surface missile range. Other fleet surface RADAR systems only

detect a “contact,” with no ability to discern between a merchant vessel and an 18-inch

periscope.

The CSGs have lost the ability to drop up to 60 sonobuoys and multiple torpedoes

on an enemy submarine from a single asset. Several helicopters would be forced to

launch to drop a comparable number of sensors and weapons.

Additionally, the CSGs no longer have the ability to send out long-range, fixed-

wing aircraft to sweep projected carrier transit waters up to 300 nautical miles in front of

the strike group. In order to cleanse an equivalent water space, CSG commanders are

forced to disperse submarines, destroyers, cruisers and frigates in an expensive effort to

perform the work originally accomplished by a crew of four on a single aircraft.

Finally, and perhaps most critically, with the retirement of the Vikings, the US

Navy is steadily losing personnel with the combined “corporate knowledge” of carrier

operations and airborne ASW tactics. Viking aircrews are either retiring from service or

being absorbed by other naval aviation communities. A critical portion of the “art” of

ASW is being forgotten.

The ship-based ASW replacement to the S-3B Viking is an aging fleet of

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SH-60B/SH-60F Seahawk helicopters. Like the P-3C, the Seahawks are excellent

submarine hunters and unlike the P-3C, are not limited by shore basing constraints. The

Seahawks are capable of deploying from smaller combatant ships; a capability that

provides them multiple landing pads throughout a CSG. The helicopters, however, have

inherent disadvantages which do not exist with the S-3B Vikings.

The detection, localization, fixing and tracking of a submarine is a time-

consuming business, often requiring aircraft to remain on station for several hours. The

primary disadvantage of using helicopters for the ASW mission lies in their range and

speed limitations. In order for a fully-fueled, ASW-loaded helicopter to be effective for

any significant amount of time, it must limit itself to a 50-nautical-mile range. The

Vikings provided the same services at ranges up to 300 nautical miles. Furthermore,

aircraft on ASW alert must be able to “pounce” quickly on newly detected submarine

positions and helicopters simply do not have the speed of a twin-engine jet like the

Viking.

The second disadvantage of using the Seahawks for airborne ASW lies in the fact

that they were designed as multi-mission platforms. In addition to the ASW mission, the

Seahawks have anti-shipping, special operations, combat search and rescue, and logistics

missions, making them a kind of “jack of all trades and master of none.” Training time

and resources dedicated to the ASW mission are constrained by the Seahawks’ other

multi-mission roles. Furthermore, to fulfill its multiple missions, the Seahawk requires

multiple on-board systems. The plurality of these systems necessitates a more “generic”

design in order to reduce weight. Included in the generic equipment is the ASW suite.

For example, none of the Seahawks have the periscope-sensitive ISAR RADAR and a

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majority have no MAD equipment on board. The Vikings were designed specifically for

the ASW mission and were dedicated solely to that mission during their first decade of

existence.

Finally, the Seahawk helicopters do not have the weapon and sonobuoy-carrying

capacity of the retiring Vikings; a fact that effectively requires the launching of multiple

helicopters to accomplish the same mission. The launching of more aircraft is a viable

option, except for the fact that US Navy CSGs deploy with fewer ASW helicopters than

they did S-3B Vikings. With the retirement of the Vikings, CSGs are deploying with

more land strike aircraft, while the population of ASW helicopter assets has remained the

same.

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Chapter 10

Gathering Threats

Proponents of the decommissioning of the S-3B Vikings, without a suitable fixed-

wing replacement, have argued that the submarine threat to the United States has steadily

diminished with the downfall of the Soviet Union. To some extent, from a “high seas”

standpoint, they are correct. There is not a belligerent nation in the world sending

submarines to harass US Navy Carrier Strike Groups or Expeditionary Strike Groups on

the high seas. Unfortunately for US and Allied navies, the high seas are not the focus of

gathering threats. Belligerent nations, specifically Iran, China and North Korea, have

focused their naval strategies in the littoral, or brown-water oceans immediately

surrounding coastlines. These strategies are reminiscent of the U-boat campaigns in

British waters between 1914 and 1918.

Iran, a state sponsor of terrorism and a dedicated enemy of the United States,

currently owns three Russian-built Kilo class diesel-electric submarines with a fourth

slated to join the inventory in the near future.1 Like the U-boats operating in British

waters during World War I, these submarines operate in Iranian coastal waters within the

Persian Gulf and the Gulf of Oman and have tremendous potential to wreak havoc on

world oil shipments as well as supply routes supporting OPERATION IRAQI FREEDOM.

These diesel-electric submarines practice the same tactics as the German U-boats in that

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they surface to acquire a fix on enemy shipping and must stay surfaced to charge

batteries. Unlike the German U-boats, however, the Iranian Kilos are capable of

acoustically fixing and attacking their targets while remaining submerged. Furthermore,

the Iranian Navy has observed US Naval operations in the Persian Gulf for 15 years. The

Iranians are familiar with carrier zones, combatant patrol areas, and rotation schedules.

The Iranian Navy, and in particular its submarines, presents a serious threat to US Naval

interests in the region.

North Korea is among the belligerent countries with a dedicated hatred for the

United States and has an active littoral submarine building program. The North Korean

navy currently employs 29 diesel-electric submarines of various classes that are capable

of operating beyond the littoral waters of its coastline, and 22 submarines exclusively

dedicated to coastal waters.2 Like the Iranians, the North Koreans have had the

opportunity to quietly watch the Seventh Fleet of the US Navy, based in Japan, conduct

operations over the course of decades. As in the Persian Gulf, the Pacific waters

surrounding the Korean Peninsula, China and Japan are some of the busiest shipping

waters in the world. The North Koreans have the added advantage of the United States

being focused on operations in the Middle East. The S-3B Vikings currently stationed in

Japan are set to be retired by October, 2005.

Finally, and perhaps most importantly, the Chinese Navy, like its Iranian and

North Korean counterparts, incorporates the use of nine diesel-electric submarines in its

coastal waters. Additionally however, the Chinese Navy owns one nuclear-powered

ballistic missile submarine with a second one planned for completion in the next two

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years.3 Tensions between the United States and China could increase at any time over

issues concerning Taiwan or North Korea.

All of these nations have at least a suspicion of the United States, if not an

outright hatred. All three sit astride the world’s busiest trade routes. All three have

employed World War I U-boat technologies and tactics in the development of their

submarine forces. Finally, these countries are growing increasingly proficient in

submarine operations making them more difficult to detect and track. They have the

capability and the motive to use their submarine forces in a confrontation with the United

States Navy and are actively seeking additional capability. In short, submarine threats

are gathering while the United States reduces ASW capabilities.

Notes

1 Jane’s Fighting ships 2004-2005 (Alexandria, VA.: Jane’s Information Group, 2005), 341

2 Ibid. 419 3 Ibid. 115

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Chapter 11

Conclusion

The German Navy of World War I demonstrated the effectiveness of the

submarine as an offensive weapon of war. Whether operating under prize rules or in

unrestricted submarine warfare, the U-boats inflicted heavy damage on Allied shipping

throughout the course of the war. How best to counter the U-boats was a question with

which the British Royal Navy grappled for a fruitless two and a half years. Various

strategies were devised to protect merchant and military shipping around the British Isles

by actively seeking an offensive approach to cleanse waters of U-boats. In the end, the

Royal Navy was able to defeat the U-boat campaigns through a combination of

technology and innovative strategies in the form of escorted merchant convoys and the

introduction of air power. The potential of the airplane in ASW was realized during the

Spider Web air patrols over the North Sea and in the subsequent introduction of air-

escorted convoys. The effectiveness of the new British strategies was demonstrated by

the sheer arithmetic of decreasing merchant losses in the face of increasing numbers of

U-boats at sea.

The lessons learned from the Royal Navy in the U-boat campaigns of World War

I were not lost on the United States Navy through the remainder of the twentieth century.

In addition to the search-and-attack tactics developed by the British, the US began to

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combine acoustic, electronic, infrared and magnetic technologies with air power for the

detection and tracking of Soviet submarines during the Cold War. The S-3B Viking

marked the pinnacle of airborne ASW tactics and technology when it was introduced as

the sole US Navy carrier-based aircraft designed specifically to incorporate all these

ASW technologies and tactics in one highly effective asset.

The end of the Cold War brought calls for a reduction in military expenditures in

the United States which eventually resulted in the decision to retire, without a fixed-wing

replacement, the S-3Bs. Proponents of the Vikings’ retirement cite the United States

Navy’s dominance of the world’s oceans as sufficient cause to decrease investment in

ASW capabilities. However, the rogue nations of the world - specifically China, North

Korea and Iran - are aggressively investing in their respective submarine forces. Like the

German Navy of World War I, these nations are focused on the purchase or development

of diesel-electric submarines designed to patrol coastal waters and theoretically wreak

havoc on merchant or military shipping. Coincidentally, all three nations sit astride the

busiest sea lanes on the planet. These sea lanes represent the economic life blood of the

United States as well as other nations, and are therefore the subject of robust US Naval

activity.

The divestment by the United States Navy of its only fixed-wing, carrier-based

ASW aircraft provides an exploitable critical weakness in US maritime strategy. China,

North Korea and Iran possess the technology and motivation to threaten and destroy US

merchant and military shipping. The parallels between the current Naval threats and the

U-boat campaigns of World War I are significant and numerous. The British Royal Navy

defeated the German U-boats through various strategies and tactics that, combined with

35

air power, proved the final defeat of the U-boats. That critical lesson, bought and paid

for by the blood of mariners and millions of tons of lost shipping, is being forgotten by

the United States Navy.

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Bibliography

Hallam, Sqdrn Leader T. D. The Spider Web, The Romance of a Flying-Boat Flight in the First World War. London-Melbourne: Arms and Armour Press, 1979

Halpern, Paul G. A Naval History of World War I. Annapolis, Md.: Naval Institute Press, 1994

Hough, Richard. The Great War At Sea 1914-1918. Oxford, N.Y.: Oxford University Press, 1983

Jane’s Fighting Ships 2004-2005. Alexandria, VA.: Jane’s Information Group, 2005. “The World War I Document Archive.” On line. Internet, August 1995. Available from

http://www.gwpda.org.

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