When Was the First Submarine Used in Warfare?

The Turtle, a one-man submersible designed by David Bushnell, became the first submarine used in combat when Sergeant Ezra Lee piloted it against the British warship HMS Eagle in New York Harbor on September 7, 1776. The mission failed because Lee could not attach an explosive charge to the ship's copper-clad hull. The Turtle was powered by hand-cranked propellers and could submerge using a foot-operated valve that flooded a water tank. Although the attack was unsuccessful, it demonstrated the potential of underwater warfare. The first submarine to actually sink an enemy vessel was the Confederate H.L. Hunley in 1864, during the American Civil War.