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historyLibrary of Congress: Inside Adams1776 · New York Harbor, USA
David Bushnell’s Secret Submarine of the American Revolution
On the night of 6 September 1776, Ezra Lee piloted the Turtle, a one-person wooden submersible designed by David Bushnell, toward the British warship HMS Eagle in New York Harbor. The plan was to screw a keg of gunpowder into the ship's hull and escape before a timer set it off. The Turtle could sink, move under water and be steered by hand, but its air ran short after about 30 minutes underwater. Lee could not drive the screw into the hull, so he gave up and the attack failed. It is still considered the first submarine used in combat, a sign of how early engineers tried to solve underwater warfare with the technology available then.
The pilot pumped water in and out of foot-operated valves to sink or rise. Depth was read from a glass tube open to the water: as the vessel went down, water rose in the tube and compressed the air, lifting a cork tipped with glowing material. Propulsion came from hand-cranked oars shaped like windmill arms.
The Turtle shows that the basic problems of submarine warfare, including depth control, air supply, propulsion and delivering a weapon, were already being tackled in the 1770s. Its failure also shows how hard those problems were with hand-powered machines.
The Turtle is considered the first submarine used in combat.
