January 31 1917 – Germany Resumes Unrestricted Submarine Warfare

Fifteen months after calling off the highly effective U-boat attacks against merchant ships nearing the British Isles, German Kaiser Wilhelm II agreed to allow unrestricted submarine warfare on January 31, 1917. The following day, the waters around Britain were once again fair game — a fact which soon turned the United States from a non-combatant to an active participant. At the start of World War I, Germany and Britain both realized the best way to affect the opposition’s warmaking capacity would be forming a blockade to prevent supplies arriving by sea. Both countries required imports of food and materiel in order to sustain a constant challenge, but the British Navy possessed far more surface ships with vastly experienced personnel, a consequence of having the largest empire in the world at the time. The Germans, however, possessed a weapon in their arsenal capable of turning the tide: the Unterseeboot. With a few dozen submarines in the inventory, Germany’s navy could project force far into the Atlantic Ocean and Mediterranean Sea without being detected. Enemy ships would literally be unable to detect the U-boats until it was too late. Early in 1915, with the British expanding minefields to choke off shipping lanes to the German coast, the Kaiser agreed to call any merchant ship in enemy waters — even those under the flag of a neutral country — a potential target. Immediately, the US government reacted with disapproval. Determined to keep the nation out of the conflict, President Woodrow Wilson sent word to his counterparts in Germany that American deaths would not be tolerated. The U-boats continued to stalk the Atlantic, setting global debate alight with the sinking of the RMS Lusitania on May 7, 1915. The Germans regarded the Cunard oceanliner as a threat due to a full load of soldiers, unaware most of the nearly 2,000 passengers were ordinary people making a voyage from New York to Liverpool. Though history has proven otherwise — there were supplies for the Allied war effort on board — the shock of almost 1,200 civilian deaths rapidly turned international opinion against Germany. In a series of letters to the Kaiser’s government, Wilson opted to avoid an open declaration of war. Using a characteristic measured tone, he laid out the rights of Americans to travel the seas and rebuffed German arguments against the British blockade before making a simple statement: any further attacks on merchant ships in which Americans were killed would be seen as “deliberately unfriendly.” By September 1915, the U-boats were back on the leash. New requirements handcuffed captains and, but for a couple of “false flag” incidents, reduced the number of confirmed torpedo kills for more than a year. By early January 1917, however, officials in the German Navy were clamoring for the ability to pursue aggressive tactics on enemy supply lines once again. The month before, Admiral Henning von Holtzendorff circulated a memo amongst top military brass containing information that a monthly rate of 600,000 tons of ships sinking, would cripple the British war effort. Leadership at Schloss Pless, the Kaiser’s residence in modern Poland, pushed to see the six-month plan put into action. Desperate to overturn the slow advance of the Allied armies, the Kaiser signed off on the strategy of permitting the 105 U-boats in service to resume unrestricted submarine warfare on January 31, 1917. Confident of success, the famous last words of von Holtzendorff’s memo echo through history as the most damaging form of hubris: “I give your Majesty my word as an officer, that not one American will land on the Continent.” The following day, attacks near the British Isles ramped up. The number of ships sank doubled from January to February, with a further 50 percent increase to 147 in March. By April, U-boats were well past the 600,000-ton goal and tightening the vise on the British population. However, that same month, Wilson received a declaration of war from Congress and mobilized the American military. Within three months, the coordination of the two navies made life much more difficult for the German submarines. A convoy system positioning destroyers alongside merchant ships allowed goods to travel safely to Britain with increasing frequency and U-boat losses began to mount. Unable to produce enough new submarines due to inadequate materials — a problem made even worse by new Allied countermeasures decreasing numbers further — U-boats were forced to end all operations on October 24, 1918. 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