190926-N-HP188-0094 ARLINGTON, Virginia (Sept. 26, 2019) Vice Adm. Thomas J. Moore, commander, Naval Sea Systems Command, places a wreath at USS Thresher (SSN 593) Commemorative Monument during a dedication ceremony in Arlington National Cemetery. The monument commemorates the service and sacrifice of the crew. Thresher sank during deep-diving tests off the coast of Massachusetts, April 10, 1963, killing all 129 personnel aboard: 16 officers, 96 enlisted sailors and 17 civilian technicians. It was the deadliest accident in submarine history, leading the Navy to establish the SUBSAFE Submarine Safety Program. (U.S. Navy photo by Mass Communication Specialist 2nd Class (SW/AW) Mutis A. Capizzi/RELEASED). (U.S. Navy photo by Mass Communication Specialist 2nd Class (SW/AW) Mutis A. Capizzi/Released)