LST-1096 was laid down on 27 November 1944 by the Jeffersonville Boat and Machinery Co., Jeffersonville, Ind., launched on 10 January 1945; sponsored by Mrs. Elizabeth L. Middleton, and commissioned on 2 February 1945, Lt. Lester W. Sperberg in command.

Following shakedown off Florida, LST-1096 prepared for duty in the Pacific. In early March, she took on pontoons and ammunition as cargo, and, on the 11th, sailed for the Panama Canal. From there, she continued on to the Marshalls, the Marianas, and the Western Carolines, arriving at Ulithi in early May. For the next two months, she supported operations in the Ryukyus; then, on 1 July, headed south to the Philippines. Most of July was spent in the Leyte area. At the end of the month, she moved up to Luzon to prepare for further amphibious operations, but, with the Japanese surrender, she returned to
Okinawa with occupation troops. Further occupation duties followed; and, into November, she carried troops and supplies from the Philippines and Okinawa to Japan. In December, carrying returning veterans as passengers and heavy equipment including one LCT as cargo, she headed east and arrived at San Francisco in mid-January 1946.

Ordered deactivated, she moved to Astoria, OR., in May for "mothballing." The ship was decommissioned on 24 August and berthed with the Reserve Fleet where she remained through the end of the decade.

In June 1950, the North Korean People's Army crossed the 38th parallel into the Republic of Korea in an attempt to unify the divided country by force. As a part of the American build up of military and naval forces to repel this Communist thrust, LST-1096 was ordered activated in August. She was recommissioned on 3 October; and, after a month at Bremerton, she moved down the coast to her home port, San Diego.

For the next two months, the LST trained out of San Diego; and, in mid-February 1951, she headed for Hawaii, Japan, and Korea. March was spent in exercising in Hawaiian waters; and, at the end of April, she arrived in Yokosuka to take up duties supporting United Nations operations in Korea. She conducted amphibious training exercises in Japanese waters, shuttled cargo and personnel between Japan and Korea; and transported prisoners of war from the South Korean mainland to the camps on the offshore islands. In November, she completed her last run and headed home.

In mid-December, LST-1096 arrived at San Diego. Overhaul, type exercises, and coastal cargo runs occupied the next eight months; and, in September 1952, the ship got underway for the Far East. By mid-October, she had arrived at Yokosuka and, a fortnight later, was conducting amphibious training exercises on the Honshu coast. She then returned to carrying cargo and personnel to Korea. She also was busy returning prisoners of war, scheduled to be exchanged, to the Korean peninsula.

After the truce agreement was reached in July 1953, LST-1096 continued her POW shuttle runs, from the camps to the mainland, and completed her last run, from Koje Do to Pusan, on 10 August. Three days later, she returned to Japan, then continued east, arriving at San Diego at the end of September.

In October, the LST shifted to Long Beach where she remained for repairs and overhaul into 1954. In January, she returned to San Diego; put back to Long Beach for further work in early February; then commenced refresher training. In April, she began moving west again, and, on the 25th, arrived in Yokosuka to begin her first peacetime western Pacific (WestPac) deployment. Through most of the summer, she conducted exercises in Japanese, Korean, and Okinawan waters. In mid-August, she was ordered south, and for three months, participated in Operation "Passage to Freedom", the transportation of people from the newly created Democratic (Communist) Republic of Vietnam, north of the 17th parallel, to the National State of Vietnam, south of that line. Operating between Haiphong and Tourane (now Danang), she completed her last run from north to south in mid-November; visited Hong Kong; then returned to Japan. In February 1955, she returned to San Diego; and, for the next eleven months, remained on the west coast.

Named St. Clair County (LST-1096) in July 1955 she sailed west again in February 1956. Training operations in Japanese, Korean, and Okinawan waters were interrupted only once, by a cruise to the Philippines in July, during her WestPac stay. In September, she moved east; and, in October, reached California.

Through the end of the 1950's and into 1960, St. Clair County rotated regularly between training exercises, cargo runs, and overhauls on the west coast and similar exercises and cargo operations with the 7th Fleet in the western Pacific. During 1960, she also participated in the making of two motion pictures: one in May while deployed to WestPac; the other in December in California coastal waters.

From 1961 to 1963, St. Clair County's schedule was altered, and her annual deployments took her only to the mid-Pacific, where she participated in amphibious exercises and conducted cargo operations for Service Force, Pacific. A FRAM II overhaul and refresher training occupied most of 1964.

In January 1965, St. Clair County resumed WestPac operations. Only briefly deployed, she departed her home port to participate in a west coast operation and ended by carrying marines and their equipment via Hawaii to Okinawa. In May, after a visit to Japan, she returned to San Diego. From mid-August to November, she retraced the itinerary she had followed from January to May. Then, through the end of the year, she remained on the west coast.

St. Clair County sailed west again on 14 January 1966, and, late in February, commenced logistic support duty for combat operations in her third war. On 25 February after a stop at Okinawa, she offloaded miscellaneous cargo, vehicles, and personnel at Chu Lai, RVN, then proceeded to Subic Bay. She briefly remained there for upkeep and loading before returning to Vietnam to operate as a unit of Task Force 76 in that embattled country's coastal waters.

In March, St. Clair County offloaded ammunition cargo at Danang; took on vehicles at Qui Nhon; and transported them to Vung Tau. On the 30th, she moved up to Saigon, and, on 4 April, returned to Vung Tau, whence she transited the Mekong and Bassac rivers to call at Can Tho. There, she discharged cargo and loaded damaged vehicles which she carried to Saigon. After another run to Can Tho, she returned to the Philippines for availability; and, in June, resumed operations in Vietnam. Through that month, she shuttled cargo between Chu Lai and Danang. In July, she underwent repairs in the Philippines; and, in August, she got underway to return to San Diego via Hong Kong, Sasebo, Yokosuka, and Pearl Harbor.

Arriving back at her home port on 23 September, St. Clair County underwent voyage repairs, then resumed exercises off the southern California coast. In the spring of 1967, she participated in exercises in Hawaiian waters, then returned to the west coast for a three-month overhaul. In November, she resumed local exercises; and, early in 1968, completed her first "over-the-beach-hi-line" evolution. In June, she headed west.

St. Clair County remained in WestPac through the remainder of the year, ferrying troops and cargo between Cua Viet and Danang and providing logistic support to riverine forces in the Mekong Delta. On 26 January she completed the cruise. Repairs and local operations followed her return to San Diego. During the summer, she conducted amphibious exercises at San Clemente and Oceanside; visited British Columbia, then returned to San Diego to prepare for inactivation. Ordered to Bremerton, she moved north and was decommissioned there on 26 September 1969. Into 1974, she remains at Bremerton as a unit of the Pacific Reserve Fleet.