The American destroyers arrived on the scene at about 17 : 00 when the U @-@ boat , U @-@ 53 under the command of Kapitänleutnant Hans Rose , was in the process of stopping the Holland @-@ America Line cargo ship Blommersdijk . Shortly after , U @-@ 53 stopped the British passenger ship Stephano . As Rose had done with three other ships U @-@ 53 had sunk earlier in the day , he gave passengers and crew aboard Blommersdijk and Stephano adequate time to abandon the ships before sinking the pair . In total , 226 survivors from U @-@ 53 's five victims was rescued by the destroyer flotilla .