U 31, Type U 43, Type U 51, Type U 57, Type U 63, Type U 66, Type Mittel U U-Cruisers and Merchant U-boats Type U 139, Type U 142, Type U 151, Type UD 1 UB coastal torpedo attack boats Type UB I, Type UB II, Type UB III, Type UF, Type UG UC coastal minelayers Type UC I, Type UC II, Type UC III UE ocean minelayers Type UE I, Type UE II Surrender of the fleet Under the terms of armistice, all U-boats were to immediately surrender. Those in home waters sailed to the British submarine base at Harwich. The entire process was done quickly and in the main without difficulty, after which the vessels were studied, then scrapped or given to Allied navies. Stephen King-Hall wrote a detailed eyewitness account of the surrender. Interwar years (1919–1939) The Treaty of Versailles ending World War I signed at the Paris Peace Conference in 1919 restricted the total tonnage of the German surface fleet. The treaty also restricted the independent tonnage of ships and forbade the construction of submarines. A submarine design office, though, was set up in the Netherlands and a torpedo research program was started in Sweden. Before the start of World War II, Germany started building U-boats and training crews, labeling these activities as "research" or concealing them using other covers. When this became known, the Anglo-German Naval Agreement limited Germany to parity with Britain in submarines. When World War II started, Germany already had 65 U-boats, with 21 of those at sea, ready for war. World War II (1939–1945) During World War II, U-boat warfare was the major component of the Battle of the Atlantic, which began in 1939 and ended with Germany's surrender in 1945. The Armistice of 11 November 1918 ending World War I had scuttled most of the old Imperial German Navy and the subsequent Treaty of Versailles of 1919 limited the surface navy of Germany's new Weimar Republic to only six battleships (of less than 10,000 tons each), six cruisers, and 12 destroyers. To compensate, Germany's new navy, the Kriegsmarine, developed the largest submarine fleet going into World War II. British Prime Minister Winston Churchill later wrote "The only thing that really frightened me during the war was the U-boat peril." In the early stages of the war, the U-boats were extremely effective in destroying Allied shipping due to the large