Actions of 5 / 6 May 1945 The last actions of the Battle of the Atlantic in American waters took place on 5 / 6 May 1945 . There were two such actions , against " U - 853 " off the Rhode Island coast , and " U 881 " , south of Cape Race , both sunk during the same period . Background . US involvement in the Battle of the Atlantic began with the deaths of 28 US citizens during the sinking of the " Athenia " by " U - 30 " , on the first day of the war in the west . Thereafter US ships were attacked , and US warships involved in action against U - boat s while protecting US interests , in the two years before America ’ s entry into the war . Following Nazi Germany ’ s declaration of war on the US on 11 December 1941 , the U - boat Arm of the " Kriegsmarine " attacked American shipping in earnest in January 1942 with Operation Drumbeat , sinking over 600 ships ( representing 3 million tons of shipping ) over a six - month period . Thereafter the U - boat Arm continued to make offensive patrols against US coastal shipping , while German wolf - packs searched for and attacked convoys in mid - ocean . By 1945 U - Boat actions had reduced to pinpricks , but their potential forced the Allies to maintain large naval and air forces , and expend considerable resources , to counter the threat . During the first five months of 1945 , the U - boat Arm dispatched 19 U - boat patrols to American waters , including seven sailings constituting group " Seewolf " , the last wolf pack of the Battle of the Atlantic . By 5 May 1945 , the day U - boat Command ( BdU ) ordered the U Boat Arm to cease hostilities , just nine were still at large ; six off the US coast , and three Seewolf boats in mid - ocean . Of these , two were involved in action with the USN , the last actions in American waters during the Atlantic campaign . First action . On 5 May , , lying in wait off Point Judith , Rhode Island , sighted and fired on SS " Black Point " , a collier underway for Boston , Massachusetts . Her torpedo es struck , and within 15 minutes , " Black Point " had capsized in of water , the last US - flagged merchant ship sunk in World War II . Twelve men died and 34 were rescued . One of the rescuing ships — SS " Kamen " — sent a report of the torpedoing that was picked up by the destroyer , destroyer escort s and , and frigate ; they discovered " U - 853 " bottomed in , and dropped more than 100 depth charge s through the night . The next morning , two blimps from Lakehurst , New Jersey — " K - 16 " and " K - 58 " — joined the attack , locating oil slicks and marking suspected locations with smoke and dye markers . " K - 16 " also attacked with rocket bombs . Finally , planking , life rafts , a chart tabletop , clothing , and an officer ' s cap floated to the surface , indicating destruction with all 55 men . " U - 853 " was destroyed at sometime between midnight , when success was first claimed , and 1225 , when it was confirmed . Second action . Also on 6 May , shortly after day - break , the destroyer escort — assigned to the hunter - killer group — detected , a " Seewolf " boat running submerged south - east of Cape Race . Making a sudden attack , " Farquhar " closed and dropped 13 depth charges in a single attack , which destroyed " U - 881 " with the loss of all hands . Conclusion . These were the last U - boats destroyed in action in American waters ; on 8 May , the Germans surrendered , and the last active U - boats in American waters gave themselves up to units of the USN and RCN .