Heron was laid down as YMS-369 on 13 January 1943 by Wheeler Shipbuilding Corp., Whitestone, New York, and launched 24 July 1943. The sponsor was Miss Frances J. McCarthy, an employee of the firm. The YMS was commissioned 11 October 1943 with Lt. Joseph R. McMahon in command. After recommissioning 15 July 1949, Heron engaged in training exercises on the U.S. West Coast until 4 October 1950 when she sailed for Korean War duty. She patrolled off the Korean Peninsula and was of invaluable assistance for her clearing of channels for blockading ships in the siege of Wonsan Harbor in March 1951.