Speed 12 k
Armament 1 3"
Endymion was laid down as LST-513, reclassified ARL-9 on 3 November 1943, launched on 17 December sponsored by Mrs. Mary C. Hanley; and commissioned on 9 May 1944, Lieutenant A. Edgell in command.
After a brief shakedown cruise in the Chesapeake Bay she sailed for Guantanamo Bay, joined a convoy headed toward the Panama Canal, and proceeded independently to San Diego. Continuing to Pearl Harbor she deployed with TG 32.6 to Guadalcanal where she arrived on 26 August 1944. She effected repairs here and at the Russell Islands before joining a task group preparing for the invasion of Palau Islands where she carried on her vital work.
From 3 October to 25 February 1945 she was active at Kossol Passage. On the latter date she sailed in convoy to Leyte where she remained for a month in the performance of diving operations and repairing of landing craft. She next proceeded with Task Unit 51.14.3 for the invasion of Okinawa and rendered invaluable service to battle- and weather-damaged destroyers, landing craft and patrol vessels. On 28 April 1945 she suffered damage from a shrapnel burst which wounded 15 of her crew.
On 10 May 1945 she changed her anchorage to Buckner Bay where she underwent frequent suicide plane attacks, but continued uninterrupted her repair service.
She got underway with Task Unit 31.29.29 for Saipan on 7 June 1945 and thence for Pearl Harbor. On 21 June she was torpedoed, suffering 11 wounded and damage to her steering gear. A subchaser was dispatched to bring her in to Eniwetok Harbor where temporary repairs were made. She continued to Pearl Harbor where she readied herself for return to the States.
Endymion began a period of overhaul at Astoria, Oreg., on 9 November 1945. She was decommissioned on 30 November 1946 and was placed in the Pacific Reserve Fleet where she remains.