Harder was a Gato-class submarine, SS-257. Electric Boat at Groton laid her down on 1 December 1941 and launched her on 19 August 1942. The Navy commissioned her on 2 December 1942. Samuel David Dealey had her from that day until he was lost with her.
On her fourth patrol, on 13 April 1944, she sank the destroyer Ikazuchi, south-southeast of Guam. Ikazuchi had been damaged off Guadalcanal in November 1942 and had gotten away.
The fifth patrol was the one the Medal of Honor cites. The submarine-loss account names three destroyers sunk on it: Minazuki on 6 June 1944, Hayanami the next day, and Tanikaze on 9 June. It says she damaged another destroyer on 10 June. The citation's count of five is the citation's. The names beyond those three are not added here. She also gave a contact report on a force leaving Tawi Tawi before the Battle of the Philippine Sea. The Presidential Unit Citation is for the first five patrols.
On 5 August 1944 she left Fremantle with Hake for a sixth patrol, west of Luzon, with Dealey in charge of the pack. At 0453 on 24 August, off Dasol Bay, Hake dived with Harder in sight to the south. Hake heard echo-ranging, then fifteen rapid depth charges, none of them close, and got away to the west. By 0955 it was quiet. Harder was never heard from again. Japanese records describe an antisubmarine attack that day, and oil, wood chips, and cork on the water. The ship that sank her is not named. She is not credited to one ship. Dealey was lost with the crew.