The USS San Marcos (LSD-25) was a Casa Grande-class dock landing ship constructed for the United States Navy during World War II. Her keel was laid on September 1, 1944, at the Philadelphia Navy Yard, and she was launched on January 10, 1945. The vessel was commissioned on April 15, 1945, and measured approximately 450 feet in length, with a beam of about 84 feet, and a draft of roughly 14 feet. She was designed to carry and launch various landing craft, including mechanized landing craft (LCM-6s), personnel landing craft (LCVPs), and large personnel landing craft (LCPLs), serving as both a transport and a drydock for amphibious operations. Following her commissioning, San Marcos completed shakedown in May 1945 before embarking on her initial deployment to the Pacific Theatre. She arrived at Pearl Harbor in June, loaded landing craft, and participated in operations around Okinawa and Japan, including repairs and cargo transport for occupation forces. Notably, she was involved in Operation Crossroads in 1946, assisting with preparations and support for atomic tests at Bikini Atoll. Afterward, she resumed cargo operations along the U.S. West Coast and in the Aleutian Islands. Decommissioned in December 1946, she was later recommissioned in January 1951 following the outbreak of the Korean War. During her second active period, she operated with the Atlantic Fleet, participating in Arctic resupply missions, Mediterranean deployments with the Sixth Fleet, and various exercises along the east coast and Caribbean. In 1958, she was deployed again to the Mediterranean, and in 1962–63, underwent a Fleet Rehabilitation and Modernization (FRAM II) overhaul to enhance her capabilities, including helicopter operations. Throughout the 1960s, USS San Marcos supported numerous NATO exercises, amphibious operations, and Cold War missions, including involvement in the Bay of Pigs invasion in 1961. She also supported Project Mercury recovery efforts and participated in Operation Inland Seas in the Great Lakes. Her service extended into the early 1970s, after which she was transferred to the Spanish Navy, renamed Galicia (TA31), and served until 1988 before being scrapped in 1989. Her career exemplifies the versatility and significance of dock landing ships in mid-20th-century naval operations.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.