On 1 July 1939 the United States Lighthouse Service became a part of the United States Coast Guard. On 1 October 1940 Fir was commissioned as the United States Coast Guard Cutter Fir (WAGL-212). With the onset of World War II Fir was assigned to the U.S. Department of the Navy and painted battleship grey. The following armament was installed for war service: M2 Browning machine guns, a 3 inch gun, and depth charges. Her wartime duties included picket duty, towing gunnery targets, and patrolling the Washington and Oregon coasts. In 1965, Fir was reclassified as a USCG coastal buoy tender (WLM).