Connecticut Governor Jonathan Trumbull recommended the invention to George Washington, who provided funds and support for the development and testing of the machine.

By early 1775, he had created a reliable method for detonating underwater explosives, a clockwork connected to a musket firing mechanism, probably a flintlock, adapted for the purpose.

[1] After the Battles of Lexington and Concord in April 1775, Bushnell began work near Old Saybrook on a small, individually manned submersible designed to attach an explosive charge to the hull of an enemy ship, which, he wrote Benjamin Franklin, would be, "Constructed with Great Simplicity and upon Principles of Natural Philosophy.

[4] He had both designed and manufactured complicated brass-wheel hall-clocks, a mahogany printing-press in 1769 (the first made in America, after Doolittle successfully duplicated the iron screw),[6][7] brass compasses, and surveying instruments.

At the start of the American Revolution, the wealthy and patriotic Doolittle built a gunpowder mill with two partners in New Haven to support the war, and was sent by the Connecticut government to prospect for lead.

"The boat was moved from Ezra's farm on the Westbrook Road to what is now Ayer's Point in Old Saybrook on the Connecticut River," writes historian Lincoln Diamant.

It took two hours to reach his destination, as it was hard work manipulating the hand-operated controls and foot pedals to propel the submersible into position.

The Royal Navy had recently begun installing copper sheathing on the bottoms of their warships to protect from damage by shipworms and other marine life, however the lining was paper-thin and could not have stopped Lee from drilling through it.

It seems more likely that he was suffering from fatigue and carbon dioxide inhalation, which made him confused and unable to properly carry out the process of drilling through the Eagle's hull.

He then released the charge (which he called a "torpedo", the prevailing term for underwater explosive devices prior to about 1890), "expecting that they would seize that likewise, and thus all would be blown to atoms.

Lee reported that the charge drifted into the East River, where it exploded "with tremendous violence, throwing large columns of water and pieces of wood that composed it high into the air.

[41] According to British naval historian Richard Compton-Hall, the problems of achieving neutral buoyancy would have rendered the vertical propeller useless.

[41] In the face of these and other problems, Compton-Hall suggests the entire story was fabricated as disinformation and morale-boosting propaganda, and if Lee did carry out an attack it was in a covered rowing boat rather than Turtle.

[41] Despite Turtle's failure, Washington called Bushnell "a Man of great Mechanical Powers, fertile of invention and a master in execution."

In retrospect, Washington observed in a letter to Thomas Jefferson, "[Bushnell] came to me in 1776 recommended by Governor Trumbull (now dead) and other respectable characters…Although I wanted faith myself, I furnished him with money, and other aids to carry it into execution.

I then thought, and still think, that it was an effort of genius; but that a combination of too many things were requisite…"[42] Turtle's attack on Eagle reflected both the ingenuity of American forces after the fall of New York and the tendency of the weaker belligerent to adopt and embrace new, sometimes radical, technologies.

"What astonishment it will produce and what advantages may be made…if it succeeds, [are] more easy for you to conceive than for me to describe," physician Benjamin Gale wrote to Silas Deane less than a year before Turtle's mission.

In 1777, he devised mines to be towed for an attack on HMS Cerberus near New London harbor[46] and to be floated down the Delaware River in an attempt to interrupt the British fleet off Philadelphia.

When the Connecticut government refused to fund further underwater project, Bushnell joined the Continental Army as a captain-lieutenant of sappers and miners, and served with distinction for several years the Hudson River in New York.

The American inventor Robert Fulton conceived of his submarine Nautilus in the first years of the nineteenth century and took it to Europe when the United States proved largely uninterested in the design.

The monopoly over submersible technology once held by the United States was lost over time as other navies around the world modernized and adopted submarine warfare.

"[49] The Turtle remains a source of national as well as regional pride, which led to the construction of several replicas, a number of which exist in Bushnell's home state of Connecticut.

In 1976, a replica of Turtle was designed by Joseph Leary and constructed by Fred Frese as a project marking the United States Bicentennial.

"With it, Yankee ingenuity was born," observed Rick Brown, referring to the latest in a long line of commemoration that perceived the Turtle as something authentically American.

Lew Nuckols, a professor of Ocean Engineering at USNA, made ten dives, noting "you feel very isolated from the outside world.

[54][55] On August 3, 2007 three men were stopped by police while escorting and piloting a replica based on the Turtle within 200 feet (61 m) of RMS Queen Mary 2, then docked at the cruise ship terminal in Red Hook, Brooklyn.

The replica was created by New York artist Philip "Duke" Riley and two residents of Rhode Island, one of whom claimed to be a descendant of David Bushnell.

Police Commissioner Raymond W. Kelly, calling this an incident of "marine mischief" assured the public that this was simply an art project and did not, in fact, represent a terrorist threat to the passenger ship.

[56] In 2015, the replica built by Manstan and Frese in 2007 for The Turtle Project was acquired by Privateer Media and used in the television series TURN: Washington's Spies.

Also in 2015, Privateer Media used The Turtle Project replica for the Travel Channel series Follow Your Past, hosted by Alison Stewart.