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Mr. Jackson is a former submariner, qualified on USS LOS ANGELES, (SSN 688). He is currently a student of American history in the Master program at Providence College

If you need to drive in a nail and you don’t have a hammer it is possible to bang the nail in with a wrench. It’s not always successful and it’s hard on the wrench but if the wrench is the only tool available, you use it. In the Great War, the UNTERSEEBOOT (U-boat) was the wrench that Imperial Germany used to bang the nail of naval offensive warfare. This examination will analyze the motive for fundamentally changing the mission of this weapon platform and will attempt to determine if expediency was the rationale for the German’s choosing the U-Boat as their primary offensive weapon.

At the onset of the Great War, the Imperial German Navy had twenty-eight submarines, and of these, twelve were of the long-range, ocean-going type and the rest were of the short-range, coastal defense type.’ Undersea warfare research was still very much in its infancy and Germany, though their total number of U-boats was small, was at the forefront of submarine research and development. Limitations in speed, weaponry and crew support features of the earliest models made it impossible for these boats to travel with the fleet and rendered them as purely defensive weapons. Many pre-war versions of German submarines were propelled by gasoline or paraffin-oil engines making them shorter range, dangerous to operate, and easy to locate on the surface by their plumes of smoke. Conditions on board were unpleasant, especially for longer duration cruises. Johannes Speiss, watch officer of the U-9 wrote, “It was really like living in a damp cellar.” These early submarines were always assumed to be close to their homeport or chaperoned by a support craft or submarine tender since their range was understood to be very limited.

Grand Admiral von Tirpitz, Secretary of State of the Imperial Naval Office, was not a supporter of U-boats as an offensive component of his battle fleet and refused to waste money on submarines “so long as they could only cruise in home waters…” But once sea going, long range submarines were available, according to the Admiral he “was the first to encourage them on a large scale” and supported their increased production” …as far as the limits of our technical production would allow.” Indeed, the U-boats, and all submarines of this period, were odd and fragile things. But the technology evolved rapidly and as the war progressed, the Imperial German U-boat became an effective ocean-going weapon. The introduction of the diesel engine, increased torpedo load and improved cruising range evolved these coastal defenders into true ocean-going predators. Submarine construction, also in its infancy, prevented the rapid production of replacement submarines, additions to the fleet, or improved models. In 1914, submarines were thought to be excellent support craft to defend harbor and coastal regions, but for the U-boats of the Imperial German Navy, this role would quickly change.

Three events at the end of 1914 caused the elevation of the U-boat from support craft to preeminent offensive weapon. First, on August 6, 1914, a ten U-boat flotilla was sent on a mission to the Orkney Islands in search of British battleships. In terms of tangible results the mission was a failure, and two of the boats never returned, but the mission created a panic in the British fleet when the astonishing range of the German submarines became evident. So startling was the presence of U-boats at such a distance from home, British Admiral of the Fleet Jellicoe commented that when U-boats were first sighted outside the North Sea, it was presumed that they must be supported by an unknown forward base or by submarine tender ships The Royal Navy battle-fleet retreated from its base at Scapa Flow, to Loch Ewe and then again to Loch Swilly, each relocation more remote from the anticipated scene of conflict in the North Sea. Speaking of this panicked retreat Winston Churchill said; “The idea had got round – “the German submarines were coming after them into their harbors.” Thus, due to their improved range and the perceived danger, the U-boat became a credible threat to the British surface fleet even before the first torpedo had been fired.

The second event was the shocking fact that U-boats could engage and defeat British warships. On September 5, 1914 Captain Hersing commanding the U-21 encountered and sunk the British destroyer HMS PA TH FINDER. This was the first ship to be sunk by a submarine in battle since the sinking of the USS HOUSATONIC by CSS HUNLEY during the American Civil War. Less than three weeks later Captain Weddegen in the U-9 attacked and sunk the HMS ABOUKJR, HMS CRESSY and HMS HOGUE, all armored heavy cruisers, for a total of 36,000 tons. What makes this especially surprising is that the U-9 was one of the coastal defense type U-boats with only six torpedoes on board, a maximum depth of 164 feet, and a cruising range of a mere 3000 miles. Admiral von Tirpitz acknowledged the value of the U-boat when he said, “…the fine achievements of Weddegen (captain of the U-9), Hersing (captain of the U-21 ), and others, soon fixed the real importance of this new weapon…”

Finally, in addition to extended range and unexpected combat effectiveness was their ability to move forward the German offensive at time when all other fronts were at a stalemate. By late 1914, the German land forces were locked in the immovable grip of trench warfare. The realization was dawning that this would not be a short war and for a country enamored with the cult of the offensive there were diminishing opportunities for advancement or victories. This was especially true for the German High Seas Fleet, which spent almost the entire war in port. However, the German Admiralty could take pride in their U-boat heroes, their aquatic Storm Troopers that could boldly break through blockades and bring the war directly to the enemy.

Now that it enjoyed a new prominence in the fleet, the U-boat needed a mission. The British remote blockade conveniently provided one as the U-boat’s role was changed to a weapon of retaliation against what was considered the illegal blockade of the German trade routes. Before turning against the British merchant shipping the U-boat’s war was almost exclusively waged against British warships. Starting on February 4, 1915 with the declaration of unrestricted submarine warfare, the submarines would be bringers of the HANDELSKRlEG or commerce war against British merchant shipping. By definition, unrestricted submarine warfare is waged by the suspension of the Cruiser Rules of international law; the destruction of merchant shipping without giving prior warning. When observing these rules, the cruiser, whether a surface or subsurface combatant, was required to fire a warning shot, stop and examine the ship’s papers, and if determined to be an enemy asset, either put a crew on board and take possession, or remove the crew to safety and destroy the vessel. The tiny submarine crew could neither spare men for a prize crew nor could they take on board the merchant sailors although in some rare cases this was done. Also, the U-boat was a fragile craft, even compared to some of the lesser merchantmen and the commanders were given direction that, “The first consideration is the safety of the U-boat.” Surfacing and giving warning exposes the U-boat to attack as they give up their advantage of stealth. The insistence of the British that the Imperial German U-boat comply with cruiser conventions was little more than attempting to remove this advantage from a very effective weapon. The British First Sea Lord, Fleet Admiral Fisher seemed to accept the concept of unrestricted submarine warfare when he stated, “There is nothing else the submarine can do except sink her capture… the essence of war is violence; moderation in war is imbecility!”

Rather than to sweep the seas clean of commerce, the Imperial Germany submarine campaign of early 1915 was designed more to frighten neutral shipping from British waters by continuing the threat of U-boat attack. This first installment of unrestricted submarine warfare was not successful due to the relatively small number of U-boats available and the effective storm of propaganda that the British were able to employ, eventually causing Germany to suspend the campaign shortly after the sinking of the RMS LUSITANIA.

The British made especially good use of propaganda by characterizing the U-boat commanders as unfeeling murderers. The unfair characterization as ravening wolves may be the sole responsibility of Kapitanleutnant Walther Schwieger, commander of the U-boat that sank the RMS LUSITANIA. While there is little question that Schwieger knew the identity of the ship he was attacking as reports concerning his own crew showed reluctance to fire on “a ship carrying women and children.” The expectation that a single torpedo would sink a 30,398-ton ocean liner in fifteen minutes is like expecting to kill an elephant with a slingshot. It is possible, but very unlikely.

Due to international political pressure, Germany’s U-boats abandoned unrestricted submarine warfare and returned to cruiser rules during the period June 1916 to January 1917. Circumstances then dictated another change in the evolving role of the U-boat. Chief of the Admiralty Staff of the Imperial German Navy, Admiral Henning von Holtzendorff, presented compelling arguments in favor of resumption of unrestricted submarine warfare in his memorandum to Field Marshal von Hindenburg. His argument focused on the opportunity to significantly affect the British food supply after the crop failure of 1916 that produced an “exceptionally poor world harvest of grain”. Dr. Hermann Levy, Professor of Economics at Heidelberg, correctly identifying England’s supply of wheat as the vulnerable commodity due to the British policy of not storing large quantities but instead preferring to supply itself hand to mouth. Holtzendorff estimated that where cruiser tactics had reduced neutral tonnage arriving in Britain by 18 percent, unrestricted submarine warfare could increase this number to 39 percent. Additionally, he highlighted the declining success of the U-boats under the cruiser rules, due to armed merchantmen, and felt that “it would be irresponsible not to make use of the submarine weapon now”. Holtzendorff and the German High Command understood the possibility of drawing the Americans into the war with unrestricted submarine warfare but believed that any confrontation with the United States was an acceptable risk. “It is unlikely that it [i.e., the United States] would decide to continue war with us, since it has no means to strike at us decisively…” Holtzendorff incorrectly concluded, but acknowledged that Germany must risk war with the United States, “…because we have no choice.” While the German Admiralty believed that Great Britain could be so economically damaged by six to eight months of unrestricted submarine warfare that they would be forced to seek peace terms, Chancellor Bethmann-Hollweg believed “England will sacrifice its last man and its last shilling” before surrendering to German naval might. The German Chancellor and Minister of the Interior warned of ignoring the American potential, and even proposed that a campaign of unrestricted submarine warfare might increase British food supplies as an aroused America made sacrifices to supply its ally in ways that it would not if it remained neutral.

The resumption of unrestricted submarine warfare in April of 1917 was poorly coordinated. Though the U-boats tonnage warfare had a significant impact on the Great Britain-bound merchant shipping, it highlighted the intrinsic weakness of the submarine as stated by Vice Admiral Wolfgang Wegner of the German Navy, “The submarine can destroy sea lanes but cannot protect them. Submarines can dive under a blockade but cannot break it.” The U-boat could deny the enemy control of the sea-lanes but it alone could not make those lanes safe for Germany’s merchant fleets. But an effective submarine fleet can destroy enough shipping to prevent movement of supplies of war from reaching the enemy and eliminate enough warships to render the enemies fleet ineffective. The Germans tried and nearly succeeded in this strategy that would be proved viable by the American Pacific submarine fleet years later. Denial of the sea-Janes to the Imperial Japanese was so effective in World War II that the submarine war in the Pacific was effectively over in December of 1944.

At the same time as successes were being achieved by the German undersea forces, their geographic control of the ocean was severely reduced by the losses of the forward U-boat bases in Flanders and the Adriatic. This weakness became very evident when the U-boats were unable to stop the faster, better protected troop transports of the Americans, who as feared had entered the war in April 1917, due to their lack of strategically located bases and to the insufficient number of the U-boats themselves. The U-boat fleet reached a peak population of only 127 boats in October of 1917.

The effectiveness of Germany’s return to unrestricted submarine warfare peaked in April of 1917 when U-boats sank 881,000 tons of merchant shipping. But as early as May of 1917 the German command began receiving reports of the effectiveness of the convoy system, an early form of anti-submarine warfare, where a group of merchant ships sails together escorted by one or more warships. The April record tonnage was never again matched and, not unexpectedly, U-boat losses also began to increase. The reality that the Imperial German U-boats could not stop shipments from the United States was evidenced when the British Ambassador in Bern wrote to the foreign office, “There is no chance now that U-boat warfare will force England into peace…”

The U-boat began the Great War as an auxiliary support adjunct to the German’s High Seas Fleet. It ended the war as the major naval offensive weapon. The U-boat did not fit into any strategic plan but instead was the motivation for the changing of the strategic plan itself. Similarly to the use of poison gas, airplanes, and the unexpectedly inactive German surface fleet, the U-boat’s mission was changed as an expedient response to the unexpected and changing conditions in the naval war theater. Given the experimental nature of the technology, it would have been impossible to anticipate the uses and surprising successes that accompanied the wider U-boat applications. Grand Admiral of the Fleet von Tirpitz, the architect of Imperial Germany’s naval strategy apologizes, “The question of how the submarines were to be used could not be answered until the instrument was there itself’. They could have been used more effectively if it had been possible to divine their ultimate capabilities and the true nature of the war that they were fighting.

Thus in the Great War, due to a stagnation of offensive movement on all fronts, the surprising effectiveness of the German submarines, and the lack of other available aggressive resources, the U-boat was the wrench that ultimately was able to drive in the nail of naval offensive warfare. The completed structure was not what was planned and a better-supplied toolbox would certainly have made it sounder. But the U-boats and German naval strategy sympathetically adapted to make the best use of the tools available.

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