Following a shakedown cruise to Bermuda, "Hissem" steamed via Charleston, South Carolina to New York, where she arrived 20 March 1944. Her first combat duty was as an escort ship with convoy UGS-37, carrying vitally needed troops and supplies to the Mediterranean. The convoy departed Norfolk, Virginia 23 March and entered the Mediterranean Sea without attack. Then near Algiers the night of 11–12 April the Luftwaffe attacked. About 35 bombers and torpedo planes struck in a coordinated attack, and were repulsed by accurate gunnery and evasive chemical smoke. "Hissem's" gun crews splashed one torpedo plane and damaged another, as the escorts prevented damage to the huge convoy of transports. The only ship struck was escort ship , torpedoed but able to make port.