By Matthew Connors

The campaign against Nazi Germany is often characterized as a land battle, but Hitler also lost the war by losing the sea. The former army corporal never truly grasped the importance of sea power and did not appropriately invest in Germany’s navy. Despite this, the Kriegsmarine nearly broke Britain through its use of aggressive surface action groups (SAGs) and irregular commerce raiders. The Kriegsmarine entered a war it was ill-suited for, well before it was prepared to fight, but by employing a form of maritime compound warfare it nearly disrupted Allied sea control which would have starved Britain and the Soviet Union of seaborne supply. Germany’s near victory demonstrates the potential of compound war at sea.

Qualifying Germany’s Naval Campaign as Compound War

In compound war a commander makes use of irregular units operating out of secure bases and augments them with the threat of conventional forces that can also take on irregular operational patterns.¹ These irregular operations can force an opponent to disperse forces across a broad space to protect vital points and supply lines from irregular raiders and guerillas. This works in tandem with the presence of a regular conventional force which requires an adversary to also maintain a sizeable concentration of units to potentially counter a large-scale offensive, similar to a fleet-in-being.

This dilemma is precisely what makes it difficult to counter a compound campaign. On land, successful compound campaigns have been waged by Washington, Wellington, and Ho Chi Minh. At sea, compound war is less common, where fleets usually contest control of the sea through fleet combat actions dominated by regular units, or raid with irregulars and dispersed units. Yet, by employing a mix of both regular combatants and irregular raiders, the Kriegsmarine essentially waged compound war from 1939 to 1942.

Broadly defined, German naval forces can be split into regular and irregular combatants.² Regular surface combatants could engage the enemy battle line or decimate lightly defended convoys. Germany’s surface striking forces mainly consisted of cruisers and battleships. These warships sowed chaos among the British Admiralty and forced the Royal Navy to cover multiple convoys and large areas while hunting small groups of German combatants.³ The presence of one pocket battleship or heavy cruiser in the Atlantic generated the need for convoys to have major surface ship escorts lest they fall prey to the big guns of a German warship. The high speeds and potent offensive capabilities of the German surface fleet could induce the Allies to scatter lightly protected convoys, which limited the damage done by heavy German combatants, but exposed them to the predations of German irregulars, submarines, and aircraft. The best example of this dual threat at work was the case of Convoy PQ17, an Arctic convoy traveling to the Soviet Union in 1942. The threat of a task force led by the German battleship Tirpitz forced the dispersion of the convoy’s ships and caused their subsequent destruction in detail by submarines and the Luftwaffe.⁴

Compound war at sea enhanced the psychological threats posed by German heavy surface ships and the German irregulars. By acting aggressively, the Kriegsmarine forced the British to deploy every available ship in their fleet to hunt for a handful of German surface ships.⁵ The Germans also conducted an extensive mining campaign that sought to deprive the British of their own shipping through destruction and neutral shipping through deterrence.⁶ The strain of constant operations and a shrinking merchant fleet was designed to cripple the Royal Navy and the commerce it protected, leaving the British Isles exposed and cut off.

The Regular Naval Threat: Surface Forces

In 1939 and 1940, aggressive commerce raiding in the Atlantic and Indian oceans by German heavy ships caused panic in Britain. The deployment of the Scheer, a pocket battleship, caused the Royal Navy to dispatch an aircraft carrier and six cruisers.⁷ A subsequent cruise by the battleships Scharnhorst and the Gneisenau sank 115,000 tons of shipping in two months, forced the deployment of the British home fleet, and managed to delay convoy sailings until battleship escorts could be found.⁸ In late 1941, plans were drafted for the operation of a surface action group out of Norway coupled with a commerce raiding deployment launched out of France. The surface action group would have drawn the British home fleet away while the raiders sowed chaos on Allied shipping.⁹ These operational plans and deployments typified the German approach and were designed to spread confusion and disruption through aggressive action.

German heavy ship operations featured regular units acting in irregular ways. While any individual platform could engage a rival, they did not have enough to risk themselves in regular combat. Therefore, the Kriegsmarine sought to fight on favorable terms against lightly guarded convoys. When the German forces found themselves outmatched by convoy escorts, they would still engage, but they would often avoid wholly committing themselves to fighting a well-guarded convoy.

Despite their irregular behavior, the German surface fleet’s potential as a regular naval threat remained potent, demonstrating the power of a fleet-in-being. The retention of a German fleet also provided the British with a strategic situation in line with the compound war concept. The continued existence of German heavy units required the Royal Navy to retain a home fleet sufficient to crush a concentrated German excursion while forcing it to also protect distant supply lines against commerce raiders, even after SAG deployments effectively ended in 1942. Even as the German surface fleet was either bottled up or sunk, it remained a real threat and a constant source of British dread. While auxiliary cruisers and submarines could be dealt with by destroyers and aircraft, German battleships and cruisers demanded strong attention from the Royal Navy.

At one point early in the war the Commander-in- Chief of the Kriegsmarine, Admiral Erich Raeder, asserted that the loss of a major German capital ship was not of major significance, especially if lost as a result of “bold action.”¹⁰ Audacity, aggression, and frequent operation on the part of the capital ships was part of cultivating their threat potential and stressing the Royal Navy’s resources and leadership. Their mere existence as a fleet in being posed a threat and required the British to divert resources from anti-submarine warfare operations and convoy escort duties. German SAG deployment arguably stalled Allied convoy departures and reduced British imports far more effectively than the grinding destruction of U-boat warfare.¹¹ But after the battleship Bismarck was lost on a raiding mission in the Atlantic the utility of these heavy units shrank as Hitler became concerned about their potential loss and was unwilling to further risk them in combat.

The Irregular Subsurface Threat: Submarines

Admiral Karl Donitz, the head of the U-boat wing and eventual commander of the German Navy during WWII, conceived of a mathematical war against the British. The war of tonnage was designed to sink first British and French and later American merchant shipping quicker than it could be built. The resulting reduction in carrying capacity and goods would cripple Allied industry and force an armistice.¹²

The irregular component of the Kriegsmarine’s maritime compound warfare was executed by irregular surface and subsurface commerce raiders. These small, cheap platforms were designed to be stealthy enough to bypass the Allied naval blockade and cruise against allied shipping. Despite some false starts and early restrictions, unrestricted submarine warfare, once joined, proved theoretically possible. While British and American shipbuilding and convoy systems eventually overwhelmed the U-boat Arm’s destructive capacity, it wasn’t until 1943 that production outstripped destruction. 1943 also witnessed a sharp decrease in the U-boat’s efficacy as Allied convoy tactics, air-ASW, and the breaking of the Enigma codes proved increasingly effective at neutralizing U-boat attacks on convoys.¹³ The entry of the U.S. into the war and the increasing tactical effectiveness of ASW saved the Allies in the Atlantic.

However, had German force structure and strategy been built around commerce destruction by the time war broke out in 1939, it may have succeeded in breaking Britain.  German unrestricted submarine warfare proved ineffective, not because of tactical failings or strategic blunders by Admirals Raeder and Donitz, but because German industry, technology, and strategic cooperation proved inadequate. The incredibly small size of the U-boat Arm at the start of the war, only a sixth of the estimated force necessary to break the British, would grow as production gradually ramped up, but losses exceeded production until July of 1940. The force did not reach the necessary 300 boats until April of 1942, but only after the U.S. had entered the war and after tactical ASW was trending in favor of the allies.¹⁴

A rough estimate of the required tonnage destruction rate that could force British capitulation was 1,800,000 tons per quarter.¹⁵ Assuming a similar destruction rate, had the 82.5 deployed U-boats per quarter attained in 1944 been reflected in the average 1940 quarter, total tonnage destroyed could have amounted to 4,294,207 tons destroyed per quarter.¹⁶ Such a shock would have starved the British war machine and people. However, the German U-boat force of the first years of the war was, like the surface force, insufficient for the requirements of the German campaign.

The famed wolfpack was even temporarily abandoned after it became apparent that there were not enough U-boats to actively execute the tactic.¹⁷ As Allied ASW efforts improved, convoys became capable of inflicting heavy damage on their attackers and U-boats became increasingly subject to destruction en-route to the hunt. In 1943 the mid-Atlantic “air gap” was closed by escort carriers and Allied ASW units improved in both quantity and quality, reducing the U-boat’s destructive potential.¹⁸ The U-boat force peaked in early 1943, and production spiked to 79 new U-boats in 1944, but the window had passed.¹⁹

Organizationally, German U-boats were kept under relatively centralized control. Their limited ability to detect convoys and coordinate with other U-boats necessitated their direct operational command by Donitz and the U-boat branch in Wilhelmshaven.²⁰ Wilhelmshaven would act as a central processing hub for data, either from submarines, aircraft, spies, or auxiliary cruisers and then concentrate a number of U-boats in the vicinity of a convoy. This concentration of boats would then attack at night on the surface where they had a speed advantage over allied merchantmen. However, the Naval Staff would also give orders directly to commanders, which complicated the command and control process.²¹ Tight control and cueing was necessary to ensure U-boats made contact with as many enemy ships as possible so as to maximize their statistical impact. This control, encrypted by the Enigma and Triton cyphers, was subject to Allied penetration. When this occurred, the Allies started avoiding submarines, reducing their efficacy.

One of the most crippling deficiencies of the German strategic approach resulted from the schizophrenic nature of Nazi high command. Historian Donald Steury assessed inter-service competition between the Luftwaffe and the Kriegsmarine as a major hinderance to joint operations against Allied shipping.²² Donitz himself points to Luftwaffe chief Hermann Goering’s staunch prohibition of an independent maritime airwing and bogarting of resources as having both limited the operational capabilities of the fleet in a broad sense and the size of the U-boat arm in particular.²³ This resulted in minimal aerial scouting which frustrated Donitz’s early efforts to coordinate wolfpack operations and interdict Allied convoys.²⁴

The Kriegsmarine had a sound strategic concept, but an inadequate force that lacked joint support. Despite their fearsome reputation, the U-boat was never properly employed to its full potential, and when coupled with Allied efforts this meant the effective defeat of Germany at sea.

The Irregular Surface Threat: Auxiliary Cruisers

Auxiliary cruisers were launched to raid allied commerce but carried out a variety of support operations. These ships were converted merchantmen, altered to carry heavy armament and equipped with reconfigurable superstructures. Designed as stealth commerce raiders, there were only a few of these ships but they had an outsized impact. HSK-5, the Pinguin, sank or captured 154,619 tons of allied shipping, a total tonnage on par with some of the U-boat wing’s top performers. By comparison the U-boats sank approximately 11,023 tons per U-boat commissioned.²⁶ Comparatively, the auxiliary cruisers did quite well, between the nine ships deployed from 1940-1943: 844,321 tons of allied shipping were destroyed, or 94,035 tons per auxiliary cruiser.²⁷ Their effectiveness demonstrates the potential of such a vessel and role.

These irregular platforms had a mix of advantages and disadvantages. They were always exposed and subject to possible destruction by a curious surface combatant, the conversion process from merchant to warship was lengthy, and escaping into the Atlantic or Arctic oceans exposed them to detection and destruction by British forces. However, their high average destruction rate is reflective of their inherent capabilities. As surface vessels, they could make high speeds, could remain underway and operational for extremely long periods of time (622 days in the case of the Atlantis), and even could operate light aircraft.²⁸ The ability to operate aircraft afforded them a degree of independence not found in the U-boats, and where the U-boat was heavily dependent on outside cueing for finding targets rather than its organic search capability. Because auxiliary cruisers could operate aircraft they could expand their personal search horizons, far superior to that of the relatively low conning tower of a submarine or its sonar.

Furthermore, the expanded crew size and cargo capacity allowed these stealth platforms to execute covert auxiliary tasks. Auxiliary cruisers mined Allied harbors all over the world, supported U-boats, and captured or destroyed Allied shipping. As surface ships, their interactions with enemy merchantmen allowed them to extend operations by refueling and resupplying from the prizes.²⁹ These ships remained operational in the Atlantic slightly longer than the regular German fleet. However, like regular surface raiders, these platforms became increasingly difficult to deploy and the last attempt at a breakout failed in February of 1943.³⁰ The auxiliary cruiser was an innovative and potent tool undercut by a lack of investment and the later conservativism of the German fleet. Much like the submarine, the auxiliary cruiser was doomed by a profound lack of investment in the German fleet and Hitler’s naval hesitance.

German Naval Force Structure: Idealism at the Cost of Realism

Admiral Raeder, who led the Kriegsmarine from 1928 to 1943, was mostly responsible for the reconstruction of the German fleet in the interwar period.³¹ After Hitler seized power naval building accelerated. Light cruisers, heavy cruisers, battlecruisers, and two battleships were constructed.³² However, Raeder’s Plan Z shipbuilding program was designed to build a fleet optimized for a compound campaign against the British. The Plan Z fleet centered on a robust home fleet, several striking forces, and commerce raiders. The home fleet would be strong enough to challenge the British home fleet, thus demanding the retention of the bulk of the Royal Navy’s capital ships in home waters, while the striking forces and commerce raiders starved the British by crushing convoys and sinking lone merchants. However, Plan Z required a longer lead time than a competing fleet design plan which would have consisted of a large submarine branch and multiple pocket battleships.

Operating under the assumption that hostilities would not commence until the mid-1940s, the Germans selected Plan Z. However, the decision to launch WWII by invading Poland in early 1939 took the naval staff almost entirely by surprise. The invasion launched the Kriegsmarine into war prematurely and well before the Plan Z buildup could be completed.³³

Losses and an increasing hesitancy on the part of Hitler to risk capital ships eventually reduced the potency of the German surface force and increased the Kriegsmarine’s reliance on submarines.³⁴ However, the German Navy started the war with an insufficient submarine fleet of only 57 boats, when an estimated 300 were required for war with Britain.³⁵ Hitler’s hesitance and ignorance of the sea kept the Kriegsmarine weak, when he lost his nerve in 1942, he constrained his surface navy which then became mostly irrelevant, leaving his inadequate submarine force to carry on what was becoming a losing naval campaign.

Conclusion

Early British deficiencies gave the Kriegsmarine a chance at victory. British ASDIC (active sonar) often performed poorly; the convoy system was initially resisted, and British shipbuilding was not able to catch up to the rate of destruction until 1943.³⁶ The cancellation of the regular surface campaign in the Atlantic in late 1941 was followed by an uptick in overall British imports, despite the increase in U-boat sinkings in 1942.³⁷ Raeder and Donitz had a winning strategic concept but an inadequate force. While compound threats are typically potent, the Kriegsmarine was unable to execute a consistent, effective campaign. As ‘Fortress Europe’ began to crumble, the effectiveness of the German maritime campaign plummeted further still. Ultimately, Hitler’s strategic failings and the small size of the German fleet at the beginning of the war caused the Kriegsmarine’s failure.

The Kriegsmarine’s shortcomings were matched with Allied successes. Cracking Enigma, the reimplementation of the convoy system, the implementation of air-based ASW, and general improvements in ASW operations saved the British merchant from the U-boat, while brave men in steel ships defeated the big guns of Hitler’s surface fleet. A future war at sea against a compound threat will require much of the same: superb code breakers, clever screen commanders, effective tactics, and brave Sailors willing to grapple with any threat.

Lieutenant Matthew Conners is a 2012 graduate of the Naval Academy and a Surface Warfare Officer. He has served in USS Hopper (DDG 70) as Repair Officer and  USS Chung Hoon (DDG 93) as the Anti-Submarine Warfare Officer. He is also the recipient of the Naval Postgraduate School’s 2018 Liskin Award for excellence in National Security Studies. He graduated from the Naval Postgraduate school in 2018 with a Master of Arts in Security Studies. He is stationed in San Diego at the Surface and Mine Warfighting Development Center.

References

[1] Thomas Huber, Compound Warfare; That Fatal Knot, (Fort Leavenworth, Kansas, U.S. Army Command and General Staff College Press, 2002) https://usacac.army.mil/cac2/cgsc/carl/download/csipubs/compound_warfare.pdf vii.

[2] There were no German naval aviation assets. Gronning quickly appropriated all related maritime aircraft to the Luftwaffe and the two German aircraft carriers under construction were never completed.

Eric Raeder, My Life, trans. Henry Drexel, (Annapolis, Naval Institute Press, 1960), 154.

Robert Jackson, Kriegsmarine; The illustrated History of the German Navy in WWII, (London, Aber’s Books ltd 2001), 24.

[3] Jackson, Kriegsmarine, 23.

[4] Jackson, Kriegsmarine, 116.

[5] Terry Hughes and John Costello, The Battle of the Atlantic, (New York, The Dial Press 1977), 20.

[6] Hughes and Costello, The Battle of the Atlantic, 49.

[7] Hughes and Costello, The Battle of the Atlantic, 123.

[8] Ibid, 125.

[9] Steury, “The German Naval Offensive,” 81-83.

[10] Cajus Bekker, Hitler’s Naval War, (Garden City, Doubleday and Company 1974), 141.

[11] Sturey, “The German Naval Offensive,” 81-83. 

[12] Hughes and Costello, The Battle of the Atlantic, 38-52.

[13] Assmann, Kurt. “Why U-Boat Warfare Failed,” Foreign Affairs 28, no. 4 (1950): 659-70. doi:10.2307/20030803 665, 667.

Hughes and Costello, The Battle of the Atlantic, 304, 305.

[14] Hughes and Costello, Battle of the Atlantic, 304-305.

[15] A 1917 Imperial naval staff estimate. In Steury, The German Naval Offensive, 93.

[16] Based on a rate of 52,051 tons per quarter per U-boat deployed at a rate of 82.5 U-boats deployed in 1944. Hughes and Costello, The Battle of the Atlantic, 304-305.

[17] Ibid, 49.

Hessler, Gunter, The U-boat War in the Atlantic, 1939-1945: German Naval History, (Great Britain, Ministry of Defense 1989), 12.

[18] Jackson, Kriegsmarine, 48-55.

[19] Hughes and Costello, The Battle of the Atlantic, 304-305.

[20] Ibid, 2.

[21] Hessler, The U-Boat war in the Atlantic, 9.

[22] Ibid, 91.

[23] Karl Doenitz, Memoirs: Ten years and Twenty days, (Cleveland, World Publishing Company 1959) 132-133.

[24] Doenitz, 133-134.

[25]Ibid.

[26] Hughes and Costello, The Battle of the Atlantic, 304-305.

This includes U-boats launched after the bulk of Allied ASW efforts began to take effect.

[27] Bekker, Hitler’s Naval War, 381.

[28] Jackson, Kriegsmarine, 69.

[29] Jackson, Kriegsmarine, 69-77.

[30] Ibid, 77.

[31] Raeder, My Life, 138-139.

[32] Jackson, Kriegsmarine, 21-23.

[33] Jurgen Rohwer, “Codes and Ciphers: Radio Communication and Intelligence,” in To Die Gallantly; The Battle of the Atlantic ed. Timothy J Rynyan and Jan M. Copes, (Boulder, Westview press 1994), 38-38.

[34] Donald Steury, “The Character of the German Naval Offensive: October 1940-June 1941,” in To Die Gallantly; The Battle of the Atlantic ed. Timothy J Rynyan and Jan M. Copes, (Boulder, Westview press 1994), 81.

[35] Assmann, Kurt. “Why U-Boat Warfare Failed.” Foreign Affairs 28, no. 4 (1950): 659-70. doi:10.2307/20030803 www.jstor.org/stable/20030803 665, 667.

[36] Kurt. “Why U-Boat Warfare Failed,” 665-667.

[37] Steury, “The German Naval Offensive,” 84-87.

Featured Image: German battleship Bismarck in the Baltic Sea in May 1941. (Colorized by Irootoko, Jr.)

This article originally featured in The Submarine Review and is republished with permission.

By Ryan Hilger

Captain Gallery picked up the radio: “Ride ’em cowboy.” Lieutenant David’s boarding party worked quickly to clear the submarine and make up Pillsbury‘s towline, despite the rudder being jammed hard over and the submarine still making ten knots. Chatelain and Jenks broke off to pick up survivors. Commander Trosino, Guadalcanal‘s Chief Engineer, and another boarding party made for the submarine to begin salvage efforts. Flooded compartments and potential booby traps slowed repair efforts. Pillsbury radioed back that the destroyer didn’t have the power to maintain the tow and keep the submarine afloat. Gallery ordered Guadalcanal into position, taking up the tow. After a challenging several days, U-505 was turned over to Naval Operating Base Bermuda for evaluation.¹ The capture of U-505 on June 4th, 1944 was the zenith of Allied anti-submarine warfare efforts, indicating that German submarines would not play a decisive role in what became the final year of the war.

The Battle of the Atlantic spanned the entire duration of the war, stressing the endurance and resourcefulness of all involved, from fleet commanders to heads of state to cryptographers to ordinary seamen in anti-submarine trawlers and U-boats everywhere. British Prime Minister Winston Churchill, worth quoting at length here, frames the issue:

“The only thing that ever really frightened me during the war was the U-boat peril. Invasion, I thought, even before the air battle, would fail. After the air victory it was a good battle for us. We could drown and kill this horrible foe in circumstances favourable to us, and, as he evidently realised, bad for him. It was the kind of battle which, in the cruel conditions of war, one ought to be content to fight. But now our life-line, even across the broad oceans, and especially in the entrances to the Island, was endangered. I was even more anxious about this battle than I had been about the glorious air fight called the Battle of Britain.²           

This unforgiving war at sea challenged the conventions of Mahan and Corbett on the meaning of sea control and, in that philosophical struggle, informs strategic thought as we face asymmetric threats abroad. Several anecdotes from this long, grinding campaign provide insights as American naval forces grapple with the nascent possibility of a modern, protracted war of attrition at sea.

The Essentiality of War Games

Convoys HX-229 and SC-122 were eastbound for Britain. Their air cover had lapsed until the Liberator squadron in Iceland could reach them. The base courses of the convoys were continually altered around wolfpack locations revealed by Ultra, the Allied radio intercept and cryptanalysis program.³ But this time, the routings had placed them on a collision course with each other and three wolfpacks, the U-boats still high after battering SC-121 and HX-228 the day prior. On March 16th, 1943, they “hurled themselves like wolves first on the Halifax convoy, then on the Sydney convoy as soon as it was sighted, and finally on the great combined mass of ships.”⁴ 38 U-boats exploited the next three days, relentlessly attacking day and night, sinking 21 of 61 ships.

The massacre of convoys SC-122 and HX-229 began twenty-five years prior to the coup de main, southeast of Sicily with then Lieutenant Commander Karl Doenitz in UB-68 and his near death at the hands of a British warship escorting a convoy just out of the Suez Canal. UB-68 was hit, but managed to blow her ballast tanks to the surface, where the submarine sank beneath him, the convoy continuing on to Britain unmolested. At that moment, floating in the warm Mediterranean waters with his lifejacket and a piece of salvaged cork, Doenitz recalls,

“That last night, however, had taught me a lesson as regards basic principles. A U-boat attacking a convoy on the surface and under cover of darkness, I realized, stood very good prospects of success. The greater number of U-boats that could be brought simultaneously into the attack, the more favorable would become the opportunities offered to each individual attacker.”⁵

The seed of wolfpack tactics had been planted. Several other German submariners would come to the same conclusion independently during the Great War, but none seemed to gain traction with the German High Command. Revolutions do not come about overnight.

Doenitz would rise slowly during the interwar years, eventually being selected to take over the first reformed U-Boat Flotilla in 1935. He found like-minded officers under his command and proceeded to develop cooperative tactics. In 1937, during the German Armed Forces Maneuvers, U-boats operated for the first time together, tasked to “locate, concentrate and attack an enemy formation and convoy somewhere on the high seas to the north of the coasts of Pomerania and West and East Prussia.”⁶ The operation was wildly successful, and U-Boat Command continued with large-scale exercises into 1939, including under the review of Admiral Raeder, the Commander-in-Chief of the German Navy, until the Second World War started a few months later. The exercises provided Doenitz with the opportunity to further refine the span of control, communications, and tactics the U-boats would need in combat to bring wolfpacks to their highest potency.

Interestingly, Doenitz reveals that the British were caught largely unaware in the first year and a half of the war that the Germans were employing cooperative tactics against their convoys. Citing Captain Stephen Roskill, the eminent British naval historian, Doenitz writes,                       

“But as the numbers controlled by Admiral Doenitz increased, he was able to introduce attacks by several U-boats working together…The change caught us unawares…but the Development was, from the British point of view, full of the most serious implications since the enemy had adopted a form of attack which we had not foreseen and against which neither tactical nor technical countermeasures had been prepared.”⁷

This is shocking revelation for the preeminent Navy in the world at the outbreak of the war. The roots of this negligence, Roskill continues, are found in the interwar period:

“When British naval training and thinking in the years between the wars are reviewed, it seems that both were concentrated on the conduct of surface ships in action with similar enemy units and that the defence was also considered chiefly from the point of view of attack by enemy surface units.”⁸

Doenitz theorizes that the invention of active sonar lulled the British into thinking that oceans had been made transparent and that the submarine became instantly irrelevant.⁹ In conjunction with the technological advances, the development of wolfpack tactics also reveals the grave threat presented by sclerotic British thinking during peacetime. The bold and decentralized command of the Nelsonian navy had slowly devolved over a century into untested, theoretical doctrine, the fleet “[enjoying] a peace routine and that its title of Mistress of the Seas [not having been] seriously challenged.”¹⁰ Arthur Marder relates the state of the Royal Navy in 1897 prior to the reforms of Admiral Jackie Fisher: “the British Navy at the end of the nineteenth century, numerically a very imposing force, was a drowsy, inefficient, moth-eaten organism.”¹¹ The ramifications of stultified strategic thought and the unacknowledged strategic draw at Jutland in 1916 further ossified British tactical development for the next twenty years.¹² Doenitz, on the other hand, presents a case for the importance of war games for tactical and operational developments, and the consequences for the navies that spend the peacetime steaming around the world to “show the flag,” fueled by achievements of past wars while the guns rust from lack of meaningful combat exercises. 

Tactical Innovation and Credulity in Technology

In the Clausewitzian sense, the nature of the Battle of the Atlantic changed little over the course of the war. The merchant ships plodded along the routes provided by the Allied convoy routing commands, ever in existential peril, while the U-boats prowled about the waves in search of prey. However, a closer examination of the operational level of war provides a plethora of examples of technical innovation—focusing on the development of active sonar here—the first applications of operations research, and a clear warning about immature faith in technological advancements without any corresponding evidence of efficacy beyond first principles or development of doctrinal employment.¹³

The first hydrophones were fitted to warships for submarine detection as early as 1915, but provided such inaccurate bearings, and without a suitable close attack weapon, to render then operationally irrelevant. In September 1918, the British formed a scientific committee, the Anti-Submarine Division International Committee (Asdic) to develop echo-ranging methods to fix a submarine’s position. The system was fielded shortly before the war ended in 1918 and continued to be developed during the interwar years, now able to provide both bearing and range.¹⁴ Prime Minister Winston Churchill recalls his experience with the refined Asdic sets:

“On June 15, 1938, the First Sea Lord took me down to Portland to show me the Asdics [italics original]… Standing on the bridge of the destroyer which was using the Asdic, with another destroyer half a mile away, in constant intercourse, I could see and hear the whole process, which was the Sacred Treasure of the Admiralty, and in the culture of which for a whole generation they had faithfully preserved.”¹⁵

The British began World War II with 220 sets installed on various small combatants and trawlers, with many more sets waiting for ships to install them on—Churchill’s maritime building program would take a year or two more to reach fruition.¹⁶ Of note, Churchill does not record the doctrinal development of anti-submarine warfare in the same way that Doenitz discussed the refinement of tactical and operational doctrine for submarine wolfpacks. Doenitz records in his Memoirs the seeming blind faith by the British that the new technology would render submarines useless as a weapon of war: “in 1937 the Admiralty reported to the Shipping Defence Advisory Committee that ‘the U-boat will never again be capable of confronting us with the problem with which we found ourselves faced in 1917.”¹⁷ Churchill, at the outbreak of the war, agreed:

“I had accepted too readily when out of office the Admiralty view of the extent to which the submarine had been mastered. Whilst the technical efficiency of the Asdic apparatus was proved in many early encounters with U-boats, our anti-U-boat resources were far too limited to prevent our suffering serious losses.”¹⁸

This failure to grasp the limitations of the new technology, both in technical performance and the employment of it, required a rapid development program and the founding of operations research.¹⁹

The British anti-submarine forces had dwindled in the interwar period to less than ten percent of the forces available to the Allies at the signing of the Armistice in Versailles.²⁰ The shortage would cost them dearly in operational tempo and merchant shipping lost while waiting for the Americans to enter the war or for their own shipbuilding program to start delivering. Even with Asdics on their warships, merchant shipping losses totaled more than 900 ships and 4,000,000 tons by the end of 1940.²¹ Yet a significant inventory of Asdics still sat on shelves, waiting for ships to enter service, and in that lies another lesson for gaining superiority in the war of attrition—cooperation with allies.

Allies and the Fielding of Capabilities

In May 1940, Churchill first laid bare the British needs to President Roosevelt: “All I ask now is that you should proclaim non-belligerency, which would mean that you would help us with everything short of actually engaging armed forces. Immediate needs are, first of all, the loan of forty or fifty of your older destroyers to bridge the gap…”²² The use of mothballed destroyers seems a logical and prudent policy to pursue, but the American political scene then, records Samuel Eliot Morison, was still rooted in quasi-pacifism.²³ It would take President Roosevelt a great deal of time and political capital to secure the Lend-Lease program.

Churchill pressed again several months later, indicating how their mutual, albeit still private, goals could be served: “We can fit [the older destroyers] very rapidly with our Asdics, and they will bridge the gap of six months before our war-time new construction comes into play.”²⁴ This string of discussion would continue between Roosevelt and Churchill for the remainder of 1940, even with the offer of British crews to man and transport the destroyers across the Atlantic. President Roosevelt would eventually find a loophole in the Neutrality Act of 1939 and sign a bilateral agreement with Churchill on September 2, 1940, on the trade of fifty older American destroyers for 99-year leases for naval bases from Great Britain. British sailors would bring the American ships back to life and take the fight to their common enemy in a shining example of the importance of bringing capabilities rapidly to bear in a war of attrition to gain a tactical edge.

The Unbiased Tyranny of Geography

It is rare for terrain in war to be so unfavorable to the contesting parties. Both Sun Tzu and Clausewitz speak of the ground as preferential to a particular side depending on the value accorded to it.²⁶ The sea, however, retains the ability to be the great equalizer, especially in the modern, globalized era, while simultaneously being supremely cruel to those who lose their respect for it. The Atlantic Ocean and the martial contest for it offered different challenges for all involved—British, German, and American. For Britain, the sea was survival. For Germany, the sea presented the longest contiguous battlefront. For the Americans, the sea represented the lifeline to Britain, under constant threat which, for the majority of the war, they lacked the necessary escorts to fully protect. Not until the summer of 1943 did the Allies begin to achieve sea control. Corbett puts this battle into theoretical prospective:

“By general and permanent control [of the sea] we do not mean that the enemy can do nothing, but that he cannot interfere with out maritime trade and overseas operations so seriously as to affect the issue of the war, and that he cannot carry on his own trade and operations except at such risk and hazard as to remove them from the field of practical strategy.”²⁷

Corbett, vice Mahan, defines the heart of the struggle: “By occupying her maritime in which they terminate we destroy the national life afloat, and thereby check the vitality of that life ashore so far as the one is dependent on the other.”²⁸ Britain needed the sea for survival and Germany rightly discerned that the sea was the key to Britain’s destruction. Thus, the Battle of the Atlantic was not simply another battle on the road to victory, but rather an extended campaign at the operational level of war, and a matter of national strategic policy for all contestants.

Churchill, never shy at communicating the necessity of commerce to the survival of Britain, again indicates the British national policy to President Roosevelt: “North Atlantic transport remains the prime anxiety… I am sorry about [stopping food subsidies to Eire], but we must think of our own self-preservation, and use for vital purposes our own tonnage brought in through so many perils.”²⁹ The American policy, still protected by pre-war isolationist policies, took more time to develop. Admiral Stark, then the Chief of Naval Operations, submitted his thoughts on American grand strategy to Navy Secretary Knox in late 1940: “Our major national objectives in the immediate future might be states as preservation of the territorial, economic, and ideological integrity of the United States…the preservation of the disruption of the British Empire with all that such consummation implies…”³⁰ These views would be fully developed and codified in the American-British Conversation (ABC) agreements, first completed in March 1941.

In the years prior to the war, Germany began finalizing how they would structure the Navy to strangle the British islands. Admiral Erich Raeder, the Commander-in-Chief of the German Navy, saw the unfolding situation plainly: “Britain imported fifty million tons of goods annually and her very existence depended on the keeping open of her supply lines. An effective attack on Britain’s oversea supplies therefore had to be the main aim of any German naval building programme.”³¹ In contrast, Raeder believed that “[as] for our surface forces, they were so inferior to the enemy in strength and numbers that about all they could hope to do was go down fighting.”³² Raeder has grasped the four Clausewitizan factors of success in war.³³ This attitude shaped the shipbuilding program in the final years of prior to the war, resulting in Germany beginning the war with near four times as many submarines as all surface ships combined.³⁴ Geography shaped the battle, forcing widely distributed forces against a highly distributed threat.

For Germany, though, the execution of the maritime strategy would be anything but trivial.³⁵ The development of wolfpack tactics and the technological advances added the efforts at the tactical and operational levels, but the distances involved pressed the strategy to its limits. Due to distance, geographic positioning, maintenance, and training cycles, only eight of the 57 U-boats in commission could be engaged in the Atlantic for the first year of the war. The early fall of France and capture of the French ports on the Bay of Biscay provided a significant improvement, both in geographic position as well as the addition of dockyards and repair facilities. Doenitz summed up the strategic value of this gain:

“Before July 1940 the U-boats had to make a voyage of 450 miles through the North Sea and round the north of Great Britain to reach the Atlantic. Now they were saving something like a week on each patrol and were thus able to stay considerably longer in the actual area of operations. This fact, in its turn, added to the total number of U-boats actively engaged against the enemy. It was thanks to these direct efforts of the possession of the Biscay bases….”³⁶

The improvement in position, combined withe the building program, allowed Germany to eventually keep nearly one hundred U-boats at sea.

Control of the Sea

Captain Roskill records that the utter destruction of HX-229 and SC-122 “made a profound impression upon the British Admiralty, which later recorded that ‘the Germans never came so near to disrupting communication between the New World and the Old as in the first twenty days of March 1943.'”³⁷  Yet the German euphoria and Allied dejection would decisively reverse in the subsequent two months as the Allies shifted the balance of power with the introduction of additional long-range aircraft. Roskill recalls,

“[A] sweeping victory was gained in April and May; and of the 56 U-boats sunk in those two months 36 were destroyed by ships and aircraft operating as convoy escorts or in support of convoys. Doenitz thereupon abandoned the battle of the convoy routes. The reason was, so he said, that his losses had increased to about one-third of all the submarines at sea— losses much too high.”³⁸

Doenitz and his submarines would never again gain the upper hand.

The Allies would subsequently introduce greater measures to fight the U-boat menace, including the introduction of the hunter-killer groups like the one that captured U-505. The industrial machine in both Britain and the United States would pick up steam, churning out Liberty ships every 42 days and escorts even more rapidly, turning the tide of the battle through sheer numbers.³⁹ Control of the sea in the Corbettian sense would be achieved, but that control did not mean that hostilities would cease—quite the contrary. Both sides would continue to feed grist to the millstone until the end of the war; each side would lose roughly 30,000 Sailors or airmen.⁴⁰ Tenuous control at best.

The Battle of the Atlantic contains many more lessons for control of the sea in a war of attrition.⁴¹ But the essence of the battle should alert strategists to the necessity of exercises in merging revolutionary technologies into new doctrine and the need to deploy capabilities, not just platforms. Above all, strategists need to know that establishing and maintaining maritime superiority in today’s environment, as in the Battle of the Atlantic, is more than the capacity to destroy the enemy in a fleet action—the Battle of the Atlantic repudiated Mahan. Captain Wayne Hughes provides the simple summation: “Naval battle is attrition centered. Victory by maneuver warfare may work on land but it does not at sea. At sea, first effective attack is the aim of every tactical commander.”⁴² An enemy can fight a war of attrition at sea, a guerre de course in which he has many advantages and vulnerabilities. Force composition cannot be determined without due regard for the economic implications of the naval role in national strategy. Commanders must continue to innovate, experiment with new technologies, and evolve how they wage war at all levels. Failure to stay abreast of technology or properly incorporate it will engender strategic surprise on the battlefield, thus driving your forces from the sea, or to the bottom of it.

Lieutenant Commander Ryan Hilger is an Engineering Duty Officer and former submariner. These views are presented in a personal capacity.

References

1. “Oral History-Battle of the Atlantic. Recollections of Captain Daniel V. Gallery, USN, commander of USS Guadalcanal Task Group concerning the capture of German submarine U-505 on 4 June 1944,” Naval History and Heritage Command, August 2, 2002, https://www.history.navy.mil/research/library/oral-histories/wwii/recollections-of-captain-daniel-v-gallery.html

2. Churchill, Winston. The Second World War, Volume II: Their Finest Hour. London: Cassell & Co, Ltd., 1949, p. 529.

3. The Ultra program was the highly secretive cryptanalysis efforts to break German radio encryption. See also “Ultra and the Battle of the Atlantic.” National Security Agency. https://www.nsa.gov/news-features/declassified-documents/cryptologic-spectrum/assets/files/Ultra.pdf. Accessed on February 6, 2017.

4. Doenitz, Karl. Memoirs: Ten Years and Twenty Days. Boston, MA: De Capo Press, 1997, p. 329.

5. Ibid, p. 4.

6. Ibid, p. 21.

7.  Ibid, p. 22.

8. Ibid, p. 23.

9.  Ibid.

10. Marder, Arthur. “Admiral Sir John Fisher: A Reappraisal.” United States Naval Institute Proceedings, March 1942, https://www.usni.org/magazines/proceedings/1942-03/admiral-sir-john-fisher-reappraisal.

11. Ibid. 

12. See also: Gordon, Andrew. The Rules of the Game: Jutland and British Naval Command. Annapolis, MD: Naval Institute Press, 2013 and Hughes, Wayne. Fleet Tactics and Coastal Combat. Annapolis, MD: Naval Institute Press, 2000. Chapters 2 and 3 of Hughes, in particular, have a concise discussion of this topic.

13. This essay focuses on the development of active sonar, but the list can certainly be expanded to include technological developments on both sides: radio direction finding, acoustic torpedoes, an air induction mast, or snorkel, the mathematically-based attack tactics for bombers and depth charging, and the prodigious industrial efforts of the American shipbuilding industry to churn out the Liberty ships and destroyer escorts. A myriad of resources provide greater information on these individual developments.

14. Sternhell, Charles M. and Alan M. Thorndike. “Antisubmarine Warfare in World War II.” Operations Evaluation Group, Office of the Chief of Naval Operations, Washington D.C., 1946, p. 2. 

15. Churchill, Winston. The Second World War, Volume I: The Gathering Storm. London: Cassell & Co, Ltd., 1948, pp. 127-8.

16. Sternhell and Thorndike, p. 2.

17. Doenitz, p. 23.

18. Churchill, p. 325.

19. See Part II of Sternhell and Thorndike for an excellent exposition on the various scientific approaches to anti-submarine warfare during the Battle of the Atlantic. This section truly summarizes the first operational application of operations research, at the time a nascent field. See also: Koopman, B. O. Search and Screening: General Principles with Historical Applications. New York, NY: Pergamon Press, 1980. Budiansky, Stephen. Blackett’s War: The Men Who Defeated the Nazi U-Boat and Brought Science to the Art of Warfare. New York, NY: Vintage Books, 2013.

20. Sternhell and Thorndike, p. 2.

21. Churchill, p. 569 and Churchill, Volume II: Their Finest Hour, p. 639.

22. Churchill, Volume II: Their Finest Hour, p. 23.

23. Morison, Samuel Eliot. History of United States Naval Operations in World War II, Volume I:  The Battle of the Atlantic, 1939-1943. Edison, NJ: Castle Books, 2001, p. 33.  

24. Churchill, p. 117.

25. Ibid, p. 361.

26. Tzu, Sun. The Art of War. Edited by Basil Liddell Hart, Oxford, UK: Oxford University Press, 1971, pp. 114-115.

 Clausewitz, Carl. On War. Edited by Peter Paret. Princeton, NJ: Princeton University Press, 1989, p. 345.

27. Corbett, Julian S. Principles of Maritime Strategy. Mineola, NY: Dover Books, 2004. pp. 102-3.

28.  Ibid, p. 91.

29. Churchill, Volume I, pp. 535-6.

30. Morison, p. 42.

31. Raeder, Erich. Struggle for the Sea. London: William Kimber and Co. Ltd., 1959, p. 128.

32. Ibid, p. 136.

33. Clausewitz, p. 261.

34. Showell, Jak Mallmann. Fuehrer Conferences on Naval Affairs 1939-1945. Gloucestrshire: The History Press, 2015, p. 34.

35. See also: Showell, Jak Mallmann. Fuehrer Conferences on Naval Affairs 1939-1945. Gloucestrshire: The History Press, 2015. This collection comprises the surviving documents that Doenitz ordered preserved, not destroyed, when he headed the German government at the end of the war. The volume shows the difficulties that the German Navy faced in executing the naval component of German national strategy given Hitler’s general disposition toward ground forces and the influence of Hermann Goering and the German Air Force.

36. Doenitz, p. 112.

37. Ibid, p. 329.

38. Roskill, Stephen. “CAPROS not Convoy: Counterattack and Destroy!” United States Naval Institute Proceedings, October 1956, https://www.usni.org/magazines/proceedings/1956-10/capros-not-convoy-counterattack-and-destroy.

39. Winston, George. “The Amazing Achievement of Baltimore’s Shipyards: One Liberty Ship Every 42 Days.” War History Online. November 24, 2015. https://www.warhistoryonline.com/military-vehicle-news/baltimores-liberty-ship-legacy.html

40. Morison, Samuel Eliot. History of United States Naval Operations in World War II, Volume X:  The Battle of the Atlantic Won, May 1943 – May 1945. Edison, NJ: Castle Books, 2001, p. 363.

41. See also: Morison, Samuel Eliot. History of United States Naval Operations in World War II, Volume X:  The Battle of the Atlantic Won, May 1943 – May 1945. Edison, NJ: Castle Books, 2001, pp. 361-4. Here Morison draws conclusions about the American role in the battle, which he generally confines to the development and deployment escort carrier groups. He writes that the British and Canadian forces were on the whole more skilled and experienced than American forces, and that British and Canadian forces did more to contribute to victory in the Atlantic than did the United States. His full conclusions about the battle are worthy fodder for strategists to consider.

42. Hughes, Wayne. Fleet Tactics and Coastal Combat. Annapolis, MD: Naval

Featured Image: Colorized photo of German U-boats. (Public Domain)