The USS Segundo (SS-398) was a Balao-class submarine built for the United States Navy during World War II. Laid down on October 14, 1943, at the Portsmouth Navy Yard in Kittery, Maine, she was launched on February 5, 1944, and commissioned on May 9, 1944. The vessel was constructed with the typical Balao-class design, optimized for durability and submerged performance. Following her commissioning, Segundo underwent fitting out and trials before moving to New London, Connecticut, for training. In June 1944, she departed for the Pacific theater via the Panama Canal, arriving at Pearl Harbor in July. Her initial combat patrols began in August 1944, with her first patrol in the Philippines near Surigao Strait. During this patrol, she was mistakenly strafed by U.S. Navy planes but sustained no damage. Her first patrol was uneventful in terms of combat engagement. Segundo's second patrol in November 1944 proved more successful, sinking seven merchant ships in a convoy near Luzon Strait. She continued operations in the East China Sea, conducting multiple attacks on Japanese vessels, notably sinking the cargo ship Shori Maru on March 11, 1945. Throughout her wartime service, Segundo also engaged in lifeguard duties and sank several smaller vessels using deck gun fire and torpedoes. In her final war patrol in August 1945, Segundo encountered the Japanese I-401 submarine, the largest in the world at the time. She accepted a prize crew aboard and escorted I-401 to Tokyo Bay, where the Japanese surrendered. After the war, she traveled to the U.S. West Coast, supporting operations during the Korean War from 1950 to 1953, including deployments to the Far East. Refitted as a Fleet Snorkel submarine in 1951, Segundo continued active service through the 1950s and 1960s, participating in numerous Pacific deployments. Her activities included responding to international crises such as the Hungarian Revolution in 1956. Deemed unfit for further service in 1970, she was decommissioned and eventually sunk as a target. Throughout her service, USS Segundo earned four battle stars for World War II and one for the Korean War, marking her as a significant vessel in mid-20th-century naval history.

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