Military history


When World War I commenced in early August 1914, the German Imperial Navy had not completed its big-ship buildup. The High Seas Fleet was therefore not strong enough to sail out and confront Britain’s powerful Grand Fleet in a single, decisive battle. Nor was the Royal Navy capable of mounting a decisive attack on the Imperial Navy in its home waters. Hence a big-ship standoff ensued, during which the opposing admirals schemed ways to entrap the other’s fleet in the confined waters of the North Sea by guile and deception. The naval war between these two great maritime powers thus proceeded in a curious, cautious, and unforeseen manner. There was only a single major surface-ship battle—Jutland—and it was brief and inconclusive.

Early in the war both Germany and Great Britain deployed submarines on offensive missions. The initial forays were remarkable. German U-boats sank three British heavy cruisers (Aboukir, Hague, and Cressy) and two light cruisers (Pathfinder, Hawke) with the loss of over 2,000 men. British submarines sank the German light cruiser Hela. Both navies were thus compelled to view the submarine as a grave new threat and they reacted accordingly. The British Grand Fleet withdrew temporarily from its North Sea base in Scapa Flow to safer waters in north Ireland. The German High Seas Fleet sharply curtailed operations in its home waters, the Helgoland Bight.

The British imposed a naval blockade against Germany with the aim of shutting off the flow of war matériel. The British did not strictly observe the prize laws; even neutral ships loaded merely with food were harassed, blocked, or turned back. In retaliation, the German Naval Staff authorized German U-boats to harass Allied merchant shipping. On October 20, 1914, a U-boat, observing the prize laws, stopped, searched, and scuttled the 866-ton British freighter Glitra off Norway. A week later another U-boat, operating in the English Channel, torpedoed without warning a French steamer, Admiral Ganteaume, which was believed to be laden with troops and therefore fair game under the prize laws. In fact the ship was jammed with 2,400 Belgian refugees, including many women and children. Fortunately, it did not sink.

These two U-boat attacks on unarmed merchant ships carried profound implications for the island nation of Great Britain, entirely dependent upon her vast mercantile fleet for survival. An organized U-boat guerre de course might be ruinous. Accordingly, the British government denounced the attacks as illegal, treacherous, piratical, and immoral. Ship owners, merchants, and insurance carriers the world over joined the chorus of denunciation.

The Central Powers, composed of Germany and the Austro-Hungarian Empire, had planned to defeat France in a quick campaign, then turn about and crush czarist Russia. But the plan went awry. The armies in France bogged down in bloody trench warfare; Russia attacked from the east, creating a two-front war. Not having anticipated a long war, the Central Powers had not stockpiled large supplies of war matériel. As a result of the British blockade, by early 1915 the Central Powers were running out of iron ore and oil and other war essentials as well as food.

To this point U-boats, strictly observing the prize rules, had sunk ten British merchant ships for about 20,000 tons. Owing to the shortage of torpedoes—they were still virtually handmade—most of these sinkings had been achieved by gunfire or forced scuttling. The surprising ease of these successes had led the senior German admirals to conclude that if the prize rules were relaxed, even the small number of U-boats available for distant operations could impose an effective counterblockade on the British Isles. The mere appearance of a single U-boat, manned by only two dozen men, whether successful in the attack or not, caused great psychological alarm, compelling the enemy to devote a hugely disproportionate share of his manpower and resources to neutralize the threat. All this would severely impair Britain’s ability to carry on the war, the advocates postulated, and might result in a tit-for-tat deal in which Britain agreed to lift its blockade of Germany.

Neither the Kaiser nor his Chancellor was keen on the proposal. Germany had already incurred heavy criticism from many quarters for sinking merely ten merchant ships. A relaxation of the prize rules would doubtless draw even harsher criticism, especially from neutral nations such as the United States, which had a substantial financial interest in sea commerce and might retaliate by entering the war. Moreover, the number of U-boats available for blockading the British Isles seemed too slight. To announce a blockade and fail abjectly would be worse than no attempt at all.

And yet the proposal would not die. Its advocates argued, not without justification, that the moral arguments were no longer relevant. In its ruthless blockade of Germany, they insisted, Britain had repeatedly violated the prize rules and other traditions protecting sea commerce, most notably in refusing the passage of neutral ships carrying only food. This line of reasoning, and other arguments, finally persuaded the Kaiser and his Chancellor to authorize a U-boat blockade of Great Britain.

The stage was carefully set. The Kaiser publicly declared that from February 18, 1915, onward, the waters around the British Isles were to be considered a “war zone.” Prize rules would no longer be strictly observed. British and French merchant vessels would be sunk without warning or exceptional measures to provide for the safety of the crews. Care would be taken to spare neutrals not carrying contraband, but all neutrals would sail the waters at their own peril. U-boat skippers, the Kaiser further declared, would not be held responsible if “mistakes should be made.”

So was launched history’s first systematized submarine guerre de course. The initial results were less than impressive. In the month of February 1915, the twenty-nine U-boats of the German submarine force sank 60,000 tons of merchant shipping; in March, 80,000 tons. The weakness of the blockade lay in the small number of U-boats available. Owing to the time spent going to and from German bases and in refit, after the initial deployment it was difficult to establish organized U-boat patrol cycles that kept more than six or seven U-boats in British waters at any given time. Notwithstanding the fear and confusion and diversion of resources it precipitated, the first U-boat blockade did not achieve its main goal. First Lord Churchill declared the blockade a failure; British imports in 1915 exceeded those of 1913. The British government refused to entertain any suggestion of lifting the blockade of Germany.

With each merchant ship sinking, the cries of moral indignation intensified. Three sinkings in particular outraged the Americans: the 32,500-ton Cunard liner Lusitania on May 7, with the loss of 1,198 passengers (128 Americans) and crew; the 16,000-ton White Star liner Arabic on August 19, with the loss of 40 passengers (3 Americans); and the liner Hesperian on September 9. So violent was the reaction in the United States (U-boat crews make war “like savages drunk with blood” declared The New York Times), that in early September 1915 the Kaiser called off the blockade of Great Britain and sent many more U-boats to the Mediterranean Sea, where the hunting was less controversial and no less lucrative and there were few Americans.

With victory no closer for the Central Powers, at the beginning of 1916 the chief of the German naval staff, Admiral Henning von Holzendorff, and his Army counterpart urged the Kaiser to authorize a renewal of the British blockade. The Navy now had almost twice as many U-boats in commission (fifty-four versus twenty-nine in 1915) and ever more U-boats were coming off the slipways. The Kaiser was tempted, but the Chancellor and Foreign Minister objected, fearful of another Lusitania, which would almost certainly bring America into the war. After days of vacillation, the Kaiser sided with the Navy, but he imposed complicated restrictions. No passenger liners of any nationality were to be attacked anywhere. No cargo ships or tankers except those unmistakably armed could be attacked outside the war zone.

The renewed blockade commenced in February 1916. Notwithstanding the restrictions and complexity of the rules, all went well for the U-boats for two months: 117,000 tons sunk in February, 167,000 tons in March. Then came another costly error. On March 24 a U-boat mistook the 1,350-ton English Channel passenger ferry Sussex for a troopship and torpedoed it. The Sussex did not sink, but about eighty people were killed in the explosion, including twenty-five Americans. In response to the renewed cries of indignation and a blistering note from Washington threatening to sever diplomatic relations, the Kaiser backed down once more and, on April 24, ordered U-boats in waters of the British Isles again to adhere strictly to the prize rules. As a result, merchant ship tonnage sunk by U-boats in British waters fell sharply for the next four months.

The German submarine force had grown to substantial size by September 1916: a total of 120 boats of all types, many with larger 105mm (4.1”) deck guns. Again the military staffs urged the Kaiser to exploit this force to the fullest. Again the Kaiser vacillated, and finally yielded, but with yet a new set of rules. Skippers were to conduct only restricted submarine warfare (by prize rules) in waters of the British Isles, where there were numerous American and other neutral ships, but they were permitted to wage unrestricted submarine warfare in the Mediterranean. This third and most intense phase of the restricted U-boat war, October 6, 1916, to February 1, 1917, was highly productive for the Germans. The U-boats sank about 500 British merchant vessels for about 1.1 million tons, raising the total bag for 1916 to about 2.3 million tons, most of that of British registry.

By early 1917 the ground war had become a brutal and fruitless bloodletting for the Central Powers and there was deep and widespread unrest at home. The German military staffs urged the Kaiser to authorize unrestricted submarine warfare in all oceans and seas. Using the results achieved in the fall of 1916, the larger number of U-boats available, plus nearly ninety new boats that were to be commissioned in 1917, the naval staff calculated that with an unrestricted U-boat campaign, nearly half of Britain’s still large merchant fleet could be wiped out within five or six months, rendering her not only incapable of prosecuting the war on the continent but also leaving her population in a condition of starvation and rebellion. America be damned, the naval staff said. If she came into the war, Germany would have enough U-boats (about seventy ready for operations in the British Isles alone) to sink all her troop and supply ships before they reached Europe. By that time, too, there was no shortage of German submarine torpedoes; U-boat skippers did not have to rely so heavily on deck guns.

Turning aside peace feelers from President Wilson and others, the Kaiser approved this proposal. He announced to the world that commencing February 1, 1917, U-boats would sink on sight every merchant ship found in British territorial waters. At the same time, he assured the German military staffs that there would be no more pussyfooting or backing down, and he promulgated a radical role reversal for the surface ships of the Imperial Navy: Henceforth they were to support U-boats, rather than the other way around. “To us,” he said, “every U-boat is of such importance that it is worth using the whole available fleet to afford it assistance and support.”

Germany launched this all-out submarine guerre de course in the British Isles with multiple attacks conducted simultaneously with “utmost energy” by about sixty U-boats. To minimize detection by Allied aircraft and submarines, and counterfire from merchant ships, and to take advantage of higher speed for escape, U-boat skippers attacked at night while on the surface. The results were spectacular: 540,000 tons sunk in February, 594,000 tons in March, and an appalling 881,000 tons in April. During April alone—the grimmest month of the U-boat war—the Germans sank 423 merchant ships, of which 350 were British.* Moreover, as anticipated, the campaign scared off most of the many neutral ships trading with Great Britain.

Reflecting the growing anger and outrage in America, President Wilson reacted firmly and militantly to this all-out U-boat campaign. On the third day, February 3, 1917, he broke off diplomatic relations with Germany. At his request, on April 6 the Congress declared war on the Central Powers.

At the beginning of the war the Royal Navy possessed no special countermeasures to fight submarines. Naval tacticians wrongly assumed that since submarines would of necessity spend most of the time on the surface, they would be easy prey for gunfire and ramming. This wrong view was reinforced when the British cruiser Birmingham rammed and sank U-15, the first U-boat to be lost. But in the five months of warfare in 1914, the Royal Navy positively sank only one other U-boat, U-18. Three other U-boats were lost in 1914 (for a total of five) to unknown causes, probably mines.

Beginning in 1915, when shipping losses to U-boats began to climb significantly, the Admiralty diverted a substantial portion of its existing resources to antisubmarine warfare (A/S in Britain, ASW in America) and asked scientists, engineers, academics, and others to help develop ways to destroy U-boats. In the belief that the best defense was a strong offense, the chief ASW weapons to emerge in World War I were these:

SURFACE HUNTERS. The Admiralty sent scores, then hundreds, then thousands of surface ships out offensively scouring the oceans for U-boats. These vessels included destroyers, frigates, sloops, trawlers, yachts, and heavily armed raiders (Q-ships) disguised as tramp steamers. Some vessels were fitted with crude hydrophones—passive underwater listening devices—which could detect the engine noise of a surfaced U-boat, but only if the hunting vessels were not moving.

In 1916 many of these offensive ASW ships were armed with a new weapon called the depth charge. The best of these underwater bombs, derived from mines, contained 300 pounds of TNT or Amatol and were fitted with hydrostatic fuses which could be set to detonate the charges at 40 and 80 feet, and later 50 to 200 feet. Since early depth charges were rolled from stern tracks (or racks) and exploded at shallow depth, the attacking vessel had to put on maximum speed or risk severe damage to its stern. Therefore, slower vessels could not use the 300-pound depth charges until fuses with deeper settings had been developed. In all of 1916, British naval forces sank only two U-boats by depth charge. In 1917 and 1918, when depth charges had been improved and were much more plentiful, the kill rate by this weapon increased significantly.

AIRBORNE HUNTERS. When the war commenced, the aviation age was merely a dozen years old. The Royal Navy had acquired about fifty seaplanes and seven nonrigid airships, called “blimps,” to scout for enemy naval forces. Some of these aircraft were diverted to U-boat hunting but, owing to the unreliability of engines, slow speed, limited fuel capacity, tiny bomb loads, and other factors, they were useless against U-boats. It became apparent, however, that when an aircraft appeared near a U-boat, it dived and became essentially immobile. Hence air patrols were useful for forcing U-boats under, thus enabling ships to skirt the danger area and avoid attack. In 1915 the Royal Navy acquired much improved seaplanes (the American-designed Curtiss American) and blimps in greater numbers. These were armed with impact-fused 100- or 520-pound bombs or 230-pound ASW bombs with delayed-action fuses that exploded at a water depth of seventy feet, but the U-boat kill rate by aircraft remained essentially zero.

SUBMERGED HUNTERS. On the theory that it was wise to “send a thief to catch a thief,” the Royal Navy saturated German home waters with submarines equipped with hydrophones. The early patrols produced no confirmed kills, but the presence of British submarines in German waters, including the Baltic Sea, where German submariners trained, caused great anxiety and disrupted routines. Beginning in 1915, British submarines began to torpedo U-boats in significant numbers. The Admiralty designed and produced a small submarine (R class) specifically for U-boat hunting but it came too late. Had British torpedoes been more reliable, the submarines doubtless would have sunk many more U-boats.

MINES. From the first days of the war both sides employed moored contact mines, planted in shallow water, usually defensively but often offensively. Defensive minefields were sown to prevent enemy forces from penetrating one’s coastal waters for shore bombardment, interdiction of shipping, or invasion. Such minefields were charted and planted with great care, leaving secret safe lanes for friendly shipping and naval forces. In order to attack British shipping, U-boats often had to negotiate the periphery or heart of defensive minefields, a hazardous undertaking. Many U-boats strayed into British minefields or hit live mines that had drifted their moorings or had broken loose. Offensive mining was more complicated and often hit-or-miss. Surface vessels, operating under cover of darkness in great haste, planted mines in likely spots such as sea-lanes or sometimes even in the safe lanes of the defensive minefields, to catch opposing naval vessels or merchant ships by surprise. Later in the war, both sides employed submarines for minelaying, combining two much-feared naval weapons.

To prevent U-boats from reaching the Atlantic via the English Channel, the British sowed lines of mines across it from Dover, England, to Cape Gris-Nez, France. However, in 1915 and 1916, British contact mines were defective, and not until the Admiralty copied and mass-produced the standard German contact mine could the Dover “field” be depended upon to block the passage of U-boats. When the Dover field was finally effective, it forced U-boats destined for the Atlantic to go northabout Scotland, adding about 1,400 miles (and about seven days) to the voyage.

After the United States entered the war and offered the Royal Navy a secret mine with a magnetic fuse, the Allies put in motion a grandiose scheme to plant 200,000 such mines across the top of the North Sea from the Orkney Islands to Norway. Although American and British forces planted about 80,000 mines in this so-called Northern Barrage, most of these mines were also defective and, other than frayed nerves, caused the Germans small harm. Even so, Allied mines in all areas ranked high as U-boat killers.

RADIO INTELLIGENCE. When the war began, radio transmission or wireless telegraphy (W/T) was a new military technology at which the British excelled. Taking advantage of a lucky capture of German naval codebooks, as well as an appalling lack of sophistication in German radio procedures and security, the British thoroughly penetrated German naval communications. The British first perfected Radio Direction Finding (RDF) to pinpoint and identify German shore- and sea-based transmitters. Utilizing the captured codebooks, they “read” on a current basis most German naval transmissions. This priceless intelligence enabled the Admiralty’s secret signals-intelligence branch (known as Room 40) to track U-boat operations to a remarkable extent. A British historian wrote that by “early 1915, Room 40 knew the total strength of the U-boat fleet, the rate at which it was growing … the composition of each flotilla … the number of U-boats at sea or in port, and when and if it put to sea … losses, as evidenced by the failure of a U-boat to return, and in most cases, the size of the [U-boat] threat in any particular area.”

Still, these many and varied ASW measures were absurdly inadequate. In all of 1915 the Germans lost merely nineteen U-boats while adding fifty-two boats to the force. In 1916 the Germans lost twenty-two boats while adding 108 boats. Notwithstanding a massive British antisubmarine effort, during the first four months of 1917, the Germans lost only eleven U-boats. To then, the average monthly U-boat loss rate had been only 1.7, a continuing losing battle for Britain because the Germans were producing seven or eight new boats per month.

In the wake of the spectacular shipping losses in April 1917, Britain’s new Prime Minister, David Lloyd George, urged the Admiralty to organize British shipping into convoys, escorted by destroyers, frigates, sloops, and other ASW craft. This was hardly a new idea; defense of sea commerce by convoy was as old as the sail and, as the British naval historian John Winton put it, “as natural and as obvious a tactic as, say, gaining and keeping the weather gauge.”

The Royal Navy had opposed the formation of convoys for numerous reasons. The principal reason, Winton wrote, was that Royal Navy officers had forgotten their history—that the main purpose of the Royal Navy was to protect Britain’s sea trade. Imbued with the aggressive doctrines of the American naval theorist Alfred Thayer Mahan (and kindred souls), who postulated that control of the seas could most effectively be insured by husbanding naval assets for a single, decisive, offensive naval battle with the enemy, they opposed the diversion of naval resources to convoying, which they viewed as mundane and defensive and which, if adopted, would be an admission that Britain had, in effect, lost control of the seas to an inferior naval power.

There were other reasons. First, notwithstanding huge losses of merchant ships on their very doorstep, the Royal Navy continued to grossly underestimate the overall effectiveness of the U-boat campaign on British maritime assets. Second, the admirals insisted convoys were enormously inefficient, compelling faster ships to reduce speeds to those of slower ships, overwhelming seaport facilities during loading and unloading periods, and posing difficult organizational problems in distant, neutral ports. Third, the Admiralty doubted the ability or desire of merchant-ship captains to accept or to follow orders or to station-keep in the required tight zigzagging formations at night or in inclement weather. Fourth, the admirals held, the concentration of merchant ships into a single large body presented U-boat skippers with richer targets, which they were not likely to miss, even with poorly aimed or errant torpedoes.

With the assistance of American naval power, the Admiralty finally—and reluctantly—agreed to a test of inbound convoying in the Atlantic. The first convoy, consisting of sixteen ships, sailed from Gibraltar to the British Isles on May 10, 1917; the second of twelve ships from Norfolk, Virginia,* on May 24. The Gibraltar convoy arrived in good time without the loss of a ship. The Norfolk convoy, escorted by the British cruiser Roxburgh and six American destroyers, ran into minor difficulties. Two of the dozen ships could not maintain the convoy’s 9-knot average speed and fell out. One of these was torpedoed going into Halifax, Nova Scotia. However, the other ten ships crossed the Atlantic in foggy weather, maintaining tight formation, zigzagging all the way, and arrived safely in the British Isles.

With the results of these tests and other data in hand, in August 1917—the beginning of the fourth year of the war—the Admiralty finally adopted the convoy system. It was a smashing success. By October over 1,500 merchant ships in about 100 convoys had reached the British Isles. Only ten ships were lost to U-boats while sailing in these convoys: one ship out of 150. By comparison, the loss rate for ships sailing independently (inbound and otherwise) was one in ten. By the end of 1917, almost all of the blue-water traffic was convoyed. These convoys had been instituted in the nick of time; U-boats sank nearly 3,000 ships for 6.2 million tons in 1917, most of them sailing independently. The historian Winton wrote: “Convoying did not win the war in 1917. But it did prevent the war from being lost in 1917.”

A U-boat skipper remembered the impact of convoying on the German submarine force. Convoying, he wrote, “robbed it of its opportunity to become a decisive factor.” He continued: “The oceans at once became bare and empty; for long periods at a time the U-boats, operating individually, would see nothing at all; and then suddenly up would loom a huge concourse of ships, thirty or fifty or more of them, surrounded by a strong escort of warships of all types.” The solitary U-boat, he went on, which “had most probably sighted the convoy purely by chance,” would attempt to attack again and again, “if the commander had strong nerves” and stamina. “The lone U-boat might sink one or two of the ships,” he concluded, “or even several; but that was a poor percentage of the whole. The convoy would steam on.”

During the final twelve months of the war, convoying became the rule rather than the exception. The British and American navies established large organizations to administer convoys and provided surface and, where feasible (close to land), aircraft escorts, armed with new and improved aerial bombs. In many instances, intelligence from Room 40, accurately identifying U-boat positions, enabled the authorities to divert convoys away from U-boats. After the full convoy system was in place (outbound from the British Isles as well as inbound) in 1918, total shipping losses fell by two-thirds from 1917: 1,133 sunk. Of these, 999 sailed independently. In the ten months of naval war in 1918, only 134 ships were lost in convoy.

The United States Navy had entered the war itching for a grand, Mahan-like decisive naval battle. Like the Royal Navy, it soon discovered that was out of the question. In due course, its main efforts were directed at helping the British fight the U-boat. It provided scores of destroyers and other small vessels for ASW hunter-killer groups and convoy escort as well as minelayers for the Northern Barrage. It also sent submarines (twenty-three in all) to conduct ASW patrols in the Azores and British Isles, but neither the boats nor the crews were up to the task, and none had any success. However, the infusion of U.S. Navy surface forces during the second half of 1917 enabled the British to convoy on a large scale and contributed to a doubling of the U-boat loss rate in 1917: forty-three U-boats lost, compared with the twenty lost in the first six months.

The sharply rising U-boat loss rate and the difficulties presented by Allied convoying were merely two of many severe problems confronting the Germans in late 1917. The resources of the entire nation and those of its allies had been spent in three years of bloody, indecisive warfare. The winds of the worker-peasant revolution in Russia had carried seeds to Germany; Bolshevism (or communism) was taking root in the ranks of Germany’s exhausted and disgruntled military forces and arms workers. German soldiers were deserting by the tens of thousands; there were sporadic but ominous mutinies on Imperial Navy vessels in Wilhelmshaven, where the crews were bored with the prosaic job of escorting U-boats in and out of port. Many U-boat craftsmen in the shipyards of Kiel and Hamburg, stirred up by Red agitators, were striking or otherwise slowing construction schedules.

There was yet another problem for the U-boat force. Despite Germany’s reputation for efficiency and centralization, the numerous U-boat flotillas, based in Germany, Flanders, the Mediterranean, and elsewhere, were controlled by the fleet commanders in those areas. Thus there was no overall coordination and control of U-boat operations; no centralized authority for collecting experiences and information, and making recommendations for increasing efficiency and decreasing risks. Moreover, the fleet commanders were free to recommend U-boat design types to the naval staff. The result was that German shipyards were engaged in building far too many submarine types (large, medium, and small torpedo shooters; large, medium, and small minelayers; huge U-cruisers, etc.). Given the disparity in design and conflicting priorities, the acute shortages of building materials, coal, food, and skilled shipyard workers (too many drafted into the Army), the severe winter weather, and the ideological unrest, the naval staff could not meet U-boat production rates, let alone assure that the rates could be doubled or tripled in 1918 and 1919, as was envisioned.

And yet the U-boat force fought on with all its might and main. During the first eight months of 1918, U-boats sank an average of about 300,000 tons of Allied shipping per month, almost all of the victims sailing alone. U-boat losses rose slightly over 1917 (sixty-nine in ten months, compared with sixty-three in the twelve months of 1917), but the losses were offset by seventy new boats that came into service. Morale remained high.

By October 1918 the German war machine and economy were exhausted, and the nation was torn by riots and rebellion. With minor exceptions, the will to fight on had dissipated; a million or more men had deserted the German Army. One notable exception was the U-boat arm. It was still strong (about 180 boats afloat; numerous others in various stages of construction in the building yards); morale remained high, and its loyalty to the government was undiminished. However, in view of the deteriorating conditions at home, there was no longer any hope that the U-boat force alone could deliver a knockout blow to the Allies. As one condition of the preliminary peace negotiations, Germany recalled the entire U-boat force on October 21. The boats returned home to find the Imperial Navy crippled by widespread mutinies. In a final irony, some U-boats were directed to train their torpedo tubes on German battleships to help put down the mutinies. None, however, was ordered to shoot.

After the Central Powers surrendered and the Armistice became effective, November 11, 1918, Allied naval authorities gained access to German records and were able to compile a balance sheet on the German U-boat war. Germany had operated 351 U-boats of all types. These had sunk more than 5,000 Allied ships of all kinds (including ten battleships and eighteen heavy and light cruisers) for about 12 million tons. A total of 178 U-boats had been lost; about 5,000 officers and men had been killed, wounded, or captured. At war’s end there were 179 U-boats ready or nearly ready for operations, 224 on the building ways, and another 200 projected. Had the war continued into 1919 or beyond, and the 224 boats under construction been placed in commission, deducting the probable U-boat loss rate, the Allies would have faced a total force of about 300 U-boats in 1919 and an even larger force in 1920.

It had required an enormous Allied effort to deal with the U-boat: 3,330 surface hunter-killer ships and escorts of all kinds full- or part-time, nearly 500 aircraft, 75 blimps, scores of submarines, countless tens of thousands of mines. U-boat losses:

Surface warships       


Probable mines






Merchant ships

7 (five by ramming)



Known accidents


Unknown causes




Most of the surviving operational U-boats were distributed among the victors: 105 to Britain, 46 to France, 10 to Italy, to Belgium. It was agreed that after the U-boats had been evaluated and stripped of useful gear, all except 10 of the 46 allotted to France were to be destroyed. The U-boats on the building ways were also destroyed. And so died the German U-boat force.

The submarine, conceived initially as a coastal vessel of limited defensive capability, then employed offensively in distant waters to wage a guerre de course, had a profound impact on naval strategy. In the future, any nation desiring absolute command of the seas not only would have to deploy a surface fleet superior to that of all other nations or likely combinations of nations, but also have at hand sufficient antisubmarine resources to protect that surface fleet, and its merchant fleet as well, from submarine attack. Conversely, it would be well advised to maintain a force of submarines to assist in the subjugation or destruction of opposing naval forces and merchant fleets.

During the war, German propagandists and pulp-fiction writers and others created a U-boat mythology. It postulated that German submarines were technical marvels, unsurpassed in the world; that German submarine captains and crews were supermen, brilliant, heroic, and invincible; that the German submarine force, loyal to the Kaiser to the bitter end, had come within an ace of bringing Great Britain to her knees and thereby defeating the Allies. German pulp-fiction writers and serious historians alike enriched the mythology in the 1920s and 1930s.

Distinguished personages in the Allied camp also contributed to the U-boat mythology. Merely to neutralize the U-boat, the British naval historian Sir Julian Corbett wrote, had demanded “the greatest sea fight in history.” Onetime First Lord of the Admiralty Winston Churchill wrote (in The World Crisis) that the U-boat “rapidly undermined” the life of the British Isles and “foundations of Allied strength” and that by 1918 the danger of an Allied collapse “began to look black and imminent.” The American Ambassador in London, Walter Hines Page, wrote that “[t]he submarine menace of 1917 threatened us with absolute and irremediable disaster” and that “[t]he submarine is the most formidable thing the war has produced—by far.” The senior American naval officer in London, William S. Sims, wrote: “Could Germany have kept fifty submarines at work on the great shipping routes in the winter and spring of 1917, nothing could have prevented her from winning the war.”



What made the U-boat seem so formidable in World War I was principally the blindness and obtuseness of the British Admiralty. In the run-up to the war, it refused to accept the possibility of a submarine guerre de course and made no real preparations for one. When the war came, the Admiralty was scandalously slow in mobilizing antisubmarine technology and putting in place major weaponry, such as the patrol aircraft, the escort destroyer, the antisubmarine submarine, a gun for merchant ships, depth charges, and reliable mines and torpedoes.

A close analysis of U-boat successes shows that they sank the overwhelming majority of Allied ships not by torpedo but by deck gun in British coastal waters and in the Mediterranean Sea where maritime traffic was dense. Most of these deck guns in the early years were 88mm (3.4”). Inasmuch as the U-boat was seldom an efficient or stable gun platform and the hull was extremely vulnerable to counterfire, had the Admiralty promptly armed British merchant ships with slightly more powerful 4” guns manned by trained gun crews, only the bravest of the U-boat skippers would have sought a one-on-one gun contest, and Allied merchant ship losses doubtlessly would have diminished significantly. Several merchant ships so armed sailing in concert would have rendered a U-boat attack by deck gun virtually suicidal, forcing the Germans to attack submerged with scarce, virtually handmade torpedoes from relatively stationary positions, which were easy to evade or outrun. At the start of 1916, only about 800 British merchant ships had guns.

The most grievous British sin, of course, was the failure to promptly adopt large-scale convoying. By the time ocean convoying was fully in place, September 1917, U-boats had already sunk about 8 million of the total 12 million tons bagged in the war. Had convoying begun much earlier, British ships could have resorted to an “evasion strategy” to avoid known U-boat positions detected by British code-breakers and other intelligence, a procedure that became almost routine in late 1917 and 1918. Moreover, if most British merchant ships sailing in these convoys had been armed with guns promptly, it is unlikely that a U-boat would have attacked so formidable an opponent by gun. A rock-bottom minimum convoy escort of one destroyer or comparable vessel with gunfire superior to the U-boat would have sufficed for defense against the few that operated singly in open ocean waters. Since U-boats invariably dived on sighting aircraft and became virtually immobilized, primitive planes—even unarmed planes—would have been highly effective in escorting coastal convoys close to shore. But the Admiralty did not adopt coastal convoys until June of 1918.

The Germans were also blind and obtuse. On the strategic level, the U-boat campaign was the chief factor in bringing the United States into the war, assuring the ultimate defeat of the Central Powers. Moreover, the Germans made the mistake of launching unrestricted submarine warfare before they had anywhere near sufficient U-boats to carry it off. This resulted in an undesirable piecemeal commitment of naval power, which the Allies were able to whittle down bit by bit. On the tactical level, the Germans failed to develop promptly an anticonvoy doctrine, such as group (or “wolf pack”) night surface attacks, massing force against force at the decisive point.

Importantly, the German high command relied completely on the U-boat to interdict the flow of fresh American troops from the States to French Atlantic ports. The U-boats utterly failed in this task. In a quite awesome naval triumph which is usually overlooked, Allied maritime forces transported about 2 million soldiers from the States to France, with the loss of merely fifty-six men due to U-boats. These deaths occurred when a torpedo hit and damaged the 9,500-ton troopship Moldavia. U-boats sank two other troopships (Covington, President Lincoln), but both were returning to the States empty. As is well known, the American troops reaching France played a pivotal role in the final defeat of German armies.

The reality of the German U-boat campaign in World War I is that it failed. It caused much damage and hardship and created no little terror. However, contrary to the mythology, the campaign did not really come close to bringing Great Britain to her knees, thereby precipitating an Allied defeat. When the U-boat threat peaked in 1917, the Allies countered with massive merchant-ship building programs and convoying. As Royal Navy historian Arthur J. Marder observed,* there was never at any time in the war “widespread privation in Britain” as a result of the U-boats.

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