Williamson was an antiaircraft gunner fired at an approaching torpedo plane, remaining at his station as the aircraft crashed directly into his gun mount.

The ship was launched on 29 August 1944, sponsored by Mrs. Sherman Register, sister of Seaman First Class Williamson and commissioned on 31 October 1944.

Early in 1945, she received orders to join the U.S. Pacific Fleet and got underway on 3 January to steam via the Panama Canal to San Diego, California.

After serving on a brief antisubmarine patrol off Eniwetok, the ship steamed to Majuro on 5 April and for the next three weeks operated in the Marshall Islands.

John L. Williamson remained on patrol duty around Ulithi with an occasional escort voyage to Eniwetok with troop transports until departing on 15 July with a large convoy for Okinawa.

After screening flight operations off Japan, she carried out courier duties between Wakayama and Yokosuka until she sailed for the United States on 2 January 1946.