(AO‑121: dp. 21,880; l. 524'; b. 68'; dr. 30'; s. 16.5 k.; cpl. 52; a. none; cl. Mission Buenaventura; T. T2‑SE‑A2)
A merchant name retained. A Franciscan mission in California founded in 1769.
Mission San Diego was laid down on 20 December 1943 under a Maritime Commission contract by Marine Ship Corp., Sausalito, Calif.; launched 14 March 1944; sponsored by Mrs. E. J. Rising; and delivered 30 April 1944.
Chartered to Deconhill Shipping Co. upon delivery for operations, she spent the remainder of the war carrying fuel to our forces overseas in the Pacific. She was returned to the Maritime Commission on 29 March 1946 and laid up in the Maritime Reserve Fleet at Suisun Bay, Calif.
Acquired by the Navy 17 October 1947, she was designated. Mission San Diego (AO‑121) and placed under the operational control of the Naval Transportation Service. After 1 October 1949, she was transferred to the newly created Military Sea Transportation Service for duty as USNS Mission San Diego (T‑AO‑121). She served with MSTS until 30 December 1954 when she was returned to MARAD and laid up in the Maritime Reserve Fleet at Olympia, Wash. She was struck from the U.S. Naval Vessel Register on 22 June 1955.
Reacquired by the Navy on 3 July 1956, she was placed in service with MSTS, but served only until 16 October 1957 when she was returned to the Maritime Commission and laid up in the Maritime Reserve Fleet at James River, Va. She was struck from the U.S. Naval Vessel Register on the same date.
Sold to Hudson Waterways Corp., on 10 November 1966, she was renamed Seatrain Washington and converted into a combination train ferry and containership. Into 1969, she still serves the United States carrying cargo between the east coast of the United States and the Caribbean, and occasionally Vietnam.