Turtle was the world's first submarine used in battle. It was invented in Connecticut in 1775 by American Patriot David Bushnell as a means of attaching explosive charges to ships in a harbor. Governor Trumbull recommended the inventor to George Washington and although the commander in chief had doubts he provided funds and support for developing and testing the machine. For many people this machine was the key to help defeat the British and win the war. The Turtle was its given name though most people think it is shaped like a walnut not a Turtle.

The submarine,designed as a naval weapon,was meant to drill into a ship's hull and plant a keg containing 130 pounds of gunpowder, which would be detonated by a time fuse. Much testing was done by the inventor's brother, Ezra Bushnell, in the waters of the Connecticut River.

Named for its shape, Turtle resembled a large clam as much as a turtle; it was about 8 feet long (according to original specs), 6 feet (1.8 m) tall, and about 3 feet (0.9 m) wide, consisting of two wooden shells covered with tar and reinforced with steel bands. It submerged by allowing water into a bilge tank at the bottom of the vessel and ascended by pushing water out through a hand pump, similarly to the use of spear sack tanks in modern submarines, and was propelled vertically and horizontally by hand-cranked propellers, the first recorded use of the screw propeller for ships. It also had two hundred pounds of lead which could be released in a moment to increase buoyancy. It was manned and operated by one person. It contained enough air for about thirty minutes and had a speed in calm water of about three miles per hour.

Six small pieces of thick glass in the top were the only source of natural light. After Bushnell pondered the problem of lighting the inside of the ship and after learning that using a candle would hasten the use of the limited oxygen supply of the air inside, he solicited the help of Benjamin Franklin who cleverly hit upon the idea of using bioluminescent foxfire to provide illumination for the compass and depth meter. The light given by the material was said to be sufficient at night, though likely dimmer than expected, because the ship was cooled by the surrounding sea water and the metabolic rate of poikilothermic, heterotrophic organisms is temperature-dependent.

On the night of September 7, 1776,  Turtle, under the guidance of army volunteer Sergeant Ezra Lee, attacked Admiral Howe's flagship HMS Eagle, which was moored off what is today called Governors Island, which is due south of Manhattan. A common misconception was that Lee failed because he could not manage to bore through the copper-sheeted hull. In practice, it has been shown that the thin copper would not have presented any problem to the drill. A more likely scenario is Lee's unfamiliarity with the vessel made him unable to keep the Turtle stable enough to work the drill against the Eagle's Hull. When he attempted another spot in the hull, he was unable to stay beneath the ship, and eventually abandoned the attempt. Governors Island is off the southern vertex of Manhattan, the place where the Hudson River and the East River merge. The currents at this point would be strong and complex. The Turtle would only be able to attack ships moored here during the short period of time when the incoming tide balanced the river currents. It is possible that during the attack the tide turned and Lee was unable to compensate. He released the keg of gunpowder when British soldiers or sailors in row boats tried to pursue him. The British, suspecting a trick, gave up the pursuit.

In 1777, Lee used floating mines in an attempt to destroy the British frigate HMS Cerberus, anchored in Niantic Bay. The explosion was said to have killed several sailors but did not do much major damage to the ship.

The submarine was sunk by the British as it sat on its tender vessel, in Fort Lee, New Jersey. Years later in a letter to Thomas Jefferson, Bushnell reported he had salvaged the Turtle but later destroyed it.

No British records of any attacks by the submarine or any reports of explosions on the night of the supposed attack on HMS Eagle exist (although records of the floating mines do). The only British records are of an intercepted letter of a supposed description of the boat which was not taken seriously.

The problems of achieving neutral buoyancy would have rendered the vertical propeller useless. The route the boat would have had to take to attack HMS Eagle was slightly across the tidal stream which would in all probability have resulted in Ezra Lee becoming exhausted.

In the face of these and other problems it has been suggested that the entire story was fabricated originally as disinformation and later a morale boosting propaganda, and that if Ezra Lee did carry out an attack it was in a covered rowing boat rather than the Turtle.

A replica is on display at the Royal navy submarine museum

In 1976, a recreation was designed by Joseph Leary and constructed by Fred Frese as a Bicentennial project. It was christened by Connecticut's governor, Ella Grasso, and later tested in the Connecticut River. It is owned by the Connecticut River Museum and is currently on loan to Old Saybrook High School in Old Saybrook, Connecticut, where students under the direction of Fred Frese are currently building a working recreation of that model.

On August 3, 2007 three men were stopped by police while piloting and escorting a replica of the Turtle within 200 feet of the Queen Mary 2 without authorization at New York City's Red Hook Brooklyn cruise ship terminal. The replica was created by New York artist Philip "Duke" Riley and two men from Rhode Island, one of whom claimed to be a descendant of David Bushnell. The coast guard issued a citation for having an unsafe vessel.

Posted by Bob Wallace, who sez, now this is history.