On February 17, 1864, the 12-foot-long Confederate submersible H. L. Hunley became the first combat sub in American history to sink a surface warship, torpedoing the U.S. Navy’s three-month-old sloop-of-war USS Housatonic as it participated in the Union blockade of Charleston, South Carolina. But instead of returning home, the Hunley sank immediately after, killing all eight of the Confederate crewmen on board. It was the short-lived sub’s third and final sinking.