(LST-604: dp. 3,960; 1. 328', b. 50', dr. 11'2", s. 11.6 k.; cpl. 283; a. 1 3'', 8 40mm., 8 20mm.; cl. Portunus)
LST-604 was laid down on 28 October 1943 by the Chicago Bridge & Iron Co., Seneca, III.; launched on 20 March 1944, sponsored by Miss Bernice Moore placed in reduced commission on 3 April 1944, and placed in full commission on 8 April 1944, Lt. Comdr. H. L. Baron, USNR, in command.
The ship was originally designated LST-519 but was redesignated as LST-604 on 18 December 1943 and made her shakedown as such from 12 to 18 April 1944. She was decommissioned on 29 April at Baltimore where she entered the Maryland Drydock Co. Yard for conversion. She was again commissioned on 9 August classified as AGP-11 and named Silenus.
Silenus completed her shakedown in the Chesapeake Bay as a motor torpedo boat tender on 9 September and was routed onward for duty with the Pacific Fleet. She transited the Panama Canal on 26 September with orders to proceed to Tulagi, B.S.I. She arrived there on 27 October and tended boats of Motor Torpedo Squadron (PT) 37 until 26 December 1944 when she sailed for the Treasury Islands. She remained there for six weeks and then sailed for Espiritu Santo via Tulagi and San Cristobal.
Silenus arrived at Espiritu Santo on 23 February 1945 and remained there until 9 August serving as tender for PT Squadrons 32 and 37. On that date, she sailed for Okinawa via Guam and Saipan, arriving on 19 September. During the month, it was planned to decommission Silenus for disposal in the Pacific; however, she was routed from Okinawa to New York via Samar, P.I., Guam, and Pearl Harbor. She arrived at New York on 17 January 1946 and was decommissioned on 14 March. Silenus was struck from the Navy list on 17 April 1946 and sold to A. G. Vincent on 25 July 1947 for scrap.
Silenus received one battle star for World War II service.