LST-912 was laid down on 5 February 1944 at Hingham, Mass., by the Bethlehem-Hingham Shipyard, Inc.; launched on 22 April 1944; sponsored by Mrs. Hazel B. Leppe; and commissioned on 21 May 1944, Lt. Lloyd R. White in command.
During World War II, LST-912 was assigned to the Asiatic-Pacific theater and participated in the following operations:
Morotai landings—September 1944
Leyte landings—November 1944
Lingayen Gulf landing—January 1945
Palawan Island landings—February and March 1945
Mindanao Island landings—April 1945
Following the war, LST-912 performed occupation duty in the Far East and saw service in China until mid-January 1949. On 1 July 1955, she was redesignated Mahnomen County (LST-912) (g.v.) after a county in northwestern Minnesota. The ship was decommissioned on 25 August 1955 and assigned to the Atlantic Reserve Fleet. Recommissioned on 27 March 1963, Mahnomen County performed extensive service in Southeast Asia, including Vietnam, before she grounded at Chulai, South Vietnam, on 30 December 1966 as a result of typhoon weather. Efforts to refloat her were unsuccessful, and she was struck from the Navy list on 31 January 1967. Mahnomen County was later demolished by the Navy Support Detachment at Chulai.
LST-912 earned four battle stars for World War II service and two battle stars for the Vietnam War.