[4] After a brief fitting out period in the San Francisco Bay area, Alamosa sailed for Portland, Oregon.

She was recommissioned on 25 September and got underway on 6 October for shakedown out of San Pedro, Los Angeles.

For the duration of World War II, the vessel carried ammunition and cargo between Eniwetok, Saipan, Guam, Ulithi, Peleliu, and Leyte.

After the end of hostilities, Alamosa entered dry dock at Apra Harbor, Guam, on 1 October 1945.

She arrived at Seattle, Washington, on 27 January; was decommissioned there on 20 May 1946; and was turned over to the United States Maritime Commission's War Shipping Administration for disposal.