<P> Although the Germans claimed victory at Jutland, the British Grand Fleet remained in control at sea . It was necessary to return to effective anticommerce warfare by U-boats . Vice-Admiral Reinhard Scheer, Commander in Chief of the High Seas Fleet, pressed for all - out U-boat war, convinced that a high rate of shipping losses would force Britain to seek an early peace before the United States could react effectively . </P> <P> The renewed German campaign was effective, sinking 1.4 million tons of shipping between October 1916 and January 1917 . Despite this, the political situation demanded even greater pressure, and on 31 January 1917, Germany announced that its U-boats would engage in unrestricted submarine warfare beginning 1 February . On 17 March, German submarines sank three American merchant vessels, and the U.S. declared war on Germany in April 1917 . </P> <P> Unrestricted submarine warfare in early 1917 was initially very successful, sinking a major part of Britain - bound shipping . With the introduction of escorted convoys, shipping losses declined and in the end the German strategy failed to destroy sufficient Allied shipping . An armistice became effective on 11 November 1918 and all surviving German submarines were surrendered . Of the 360 submarines that had been built, 178 were lost, but more than 11 million tons of shipping had been destroyed . Of the 178 submarines destroyed, SM U-103 was sunk when the troopship RMS Olympic rammed it as it attempted to crash dive, killing all on board . </P> <Ul> <Li> Körting kerosene - powered boats <Ul> <Li> Type U 1, Type U 2, Type U 3, Type U 5, Type U 9, Type U 13, Type U 16, Type U 17 </Li> </Ul> </Li> <Li> Mittel - U MAN diesel boats <Ul> <Li> Type U 19, Type U 23, Type U 27, Type U 31, Type U 43, Type U 51, Type U 57, Type U 63, Type U 66, Type Mittel U </Li> </Ul> </Li> <Li> U-Cruisers and Merchant U-boats <Ul> <Li> Type U 139, Type U 142, Type U 151, Type UD 1 </Li> </Ul> </Li> <Li> UB coastal torpedo attack boats <Ul> <Li> Type UB I, Type UB II, Type UB III, Type UF, Type UG </Li> </Ul> </Li> <Li> UC coastal minelayers <Ul> <Li> Type UC I, Type UC II, Type UC III </Li> </Ul> </Li> <Li> UE ocean minelayers <Ul> <Li> Type UE I, Type UE II </Li> </Ul> </Li> </Ul>

When was the submarine first used in ww1