USS Barnett, a 9432-ton transport, was built in 1928 in England as the civilian passenger ship Santa Maria. She was purchased by the Navy in August 1940 and commissioned the following month. During the rest of 1940 and in 1941 she took part in amphibious training exercises in the Caribbean area. In 1942, following the outbreak of war between the United States and Japan, Barnett went to the Pacific, where she participated in the invasion of Guadalcanal in August and the subsequent campaign to hold that island in the face of Japanese efforts to retake it.

Reclassified as an attack transport in February 1943, with the new hull number APA-5, Barnett spent that year and the next in the Atlantic war theater. During 1943 she was part of the amphibious forces that supported the landings on Sicily in July and at Salerno in September. During the Sicily operation, on 11 July 1943, Barnett was near-missed by an enemy bomb, which damaged the ship and killed seven of the Army troops on board. The transport was also active during the Normandy invasion in June 1944 and in the invasion of Southern France in August and September 1944.

Barnett returned to the Pacific in time to participate in the Okinawa landings in April 1945 and steamed back to the United States shortly after the end of the war with Japan. In May 1946, USS Barnett was decommissioned at Newport, Rhode Island. She was transferred to the Maritime Commission in July 1946.