On 9 March 1944 the US Coast Guard manned USS Leopold (DE 319) (Cdr Kenneth C. Phillips, USCG) was on her second voyage and escorting convoy CU-16, when she got an acoustic contact about 400 miles south of Iceland and turned to investigate it. But before the destroyer escort reached the U-boat, she was hit at 22.00 hours by a Gnat from U-255 and was abandoned. The vessel broke in two and remained afloat, but both parts sank early the next morning. The commander, all twelve officers and 159 ratings were lost. Only 28 survivors and three bodies were picked up by the sister ship USS Joyce (DE 317) and taken to Londonderry.