<P> The last actions of the Battle of the Atlantic were on May 7--8 . U-320 was the last U-boat sunk in action, by an RAF Catalina; while the Norwegian minesweeper NYMS 382 and the freighters Sneland I and Avondale Park were torpedoed in separate incidents, just hours before the German surrender . </P> <P> The remaining U-boats, at sea or in port, were surrendered to the Allies, 174 in total . Most were destroyed in Operation Deadlight after the war . </P> <P> The Germans failed to stop the flow of strategic supplies to Britain . This failure resulted in the build - up of troops and supplies needed for the D - Day landings . The defeat of the U-boat was a necessary precursor for accumulation of Allied troops and supplies to ensure Germany's defeat . </P> <P> Victory was achieved at a huge cost: between 1939 and 1945, 3,500 Allied merchant ships (totalling 14.5 million gross tons) and 175 Allied warships were sunk and some 72,200 Allied naval and merchant seamen lost their lives . The Germans lost 783 U-boats and approximately 30,000 sailors killed, three - quarters of Germany's 40,000 - man U-boat fleet . </P>

Germany lost the battle of the atlantic because