Turtle (also called American Turtle) was the world's first submarine, or by modern standards a submersible, with a documented record of use in combat. It was built in 1775 by American David Bushnell as a means of attaching explosive charges to ships in a harbor, for use against the Royal Navy during the American Revolutionary War. Connecticut Governor Jonathan Trumbull recommended the invention to George Washington, who provided funds and support for the development and testing of the machine.
Several attempts were made using Turtle to affix explosives to the undersides of British warships in New York Harbor in 1776. All failed, and her transport ship was sunk later that year by the British with the submarine aboard. Bushnell claimed eventually to have recovered the machine, but its final fate is unknown. Modern replicas of Turtle have been constructed and are on display in the Connecticut River Museum, the U.S. Navy's Submarine Force Library and Museum, the Royal Navy Submarine Museum, the International Spy Museum, and the Oceanographic Museum (Monaco).
Development
American inventor David Bushnell had the idea of a submersible vessel for use in lifting the British naval blockade during the American War of Independence. Bushnell may have begun studying underwater explosions while at Yale College. 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.Diamant, p. 22
After the Battles of Lexington and Concord in April 1775, Bushnell began work near Old Saybrook on a small, individually manned submarine designed to attach an explosive charge to the hull of an enemy ship. He wrote to Benjamin Franklin that it would be "Constructed with Great Simplicity and upon Principles of Natural Philosophy."
Little is known about the origin, inspiration, and influences for Bushnell's invention. It seems clear that Bushnell knew of the work of Dutch inventor Cornelis Drebbel. According to Dr. Benjamin Gale, the many brass and mechanical parts of the submarine were built by New Haven inventor Isaac Doolittle,Diamant, p. 23 whose shop was just half a block from Yale.Manstan, p. 29
Bushnell is given the overall design credit for the Turtle by Gale and others, but Doolittle was well known as an "ingenious mechanic", engraver, and metalworker. He had designed and manufactured complicated brass-wheel hall-clocks, a mahogany printing-press,Burns, William E., Science and Technology in Colonial America, Greenwood Publishing Group, 2005, p. 90Sanjek, Russell, American popular music and its business: the first four hundred years, Oxford University Press, 1988, p. 364 brass compasses, and surveying instruments. He also owned a brass foundry where he cast bells. At the start of the American Revolution, Doolittle built a gunpowder mill with two partners in New Haven to support the war, and the Connecticut government sent him to prospect for lead.Manstan, p. 53
The design of the Turtle was necessarily shrouded in secrecy,Manstan, p. 43 but Doolittle probably designed and crafted the brass and moving parts of the Turtle,Manstan, pp. 52–53 including the propulsion system,Manstan, p. 88 the navigation instruments,Manstan, p. 120 the brass foot-operated water-ballast and forcing pumps,Manstan, pp. 57, 105, 107 the depth gauge and compass,Manstan, pp. 120–123 the brass crown hatch,Manstan, pp. 109, 110, 112 the clockwork detonator for the mine,Manstan, pp. 131, 136 and the hand-operated propeller crank and foot-driven treadle with flywheel.Manstan, pp. 194–198
According to a letter from Dr. Benjamin Gale to Benjamin Franklin, Doolittle also designed the mine attachment mechanism, "those Parts which Conveys the Powder, and secures the same to the Bottom of the Ship".Mansten, p. 138
The most historically important innovation in the Turtle was the propeller, as it was the first known use of one in a watercraft. It was described as an "oar for rowing forward or backward", with "no precedent" design.Manstan, p. 150 Benjamin Gale described it to Silas Deane as "two oars or paddles" that were "like the arms of a windmill... long, and about wide."Abbot pp. 178–180 Manstan speculates that it was made of brass and was likely designed and forged by Doolittle.Manstan, p. 93
In making the hull, Bushnell enlisted the services of several skilled artisans, including his brother Ezra Bushnell and ship's carpenter Phineas Pratt, both from Saybrook.Manstan, p. 54 The hull was "constructed of oak, somewhat like a barrel and bound by heavy wrought-iron hoops." The shape of the hull, Gale informed Silas Deane, "has the nearest resemblance to the two upper shells of a Tortoise joined together."
Turtle was about long (according to the original specifications), tall, and about wide, and consisted of two wooden shells covered with tar and reinforced with steel bands.Schecter, p. 172 It dived by allowing water into a bilge tank at the bottom of the vessel and resurfaced by pushing water out through a hand pump. It was propelled vertically and horizontally by hand-cranked and pedal-powered propellers, respectively. It also had of lead aboard, which could be released in a moment to increase buoyancy. It was manned and operated by one person and contained enough air for about 30 minutes. It had a speed in calm water of about .
Six small pieces of thick glass in the top of the submarine provided natural light. The internal instruments had small pieces of bioluminescent foxfire affixed to the needles to indicate their position in the dark. During trials in November 1775, Bushnell discovered that this illumination failed when the temperature dropped too low. He repeatedly requested that Benjamin Franklin suggest possible alternatives, but Franklin did not suggest any and Turtle was sidelined for the winter.Diamant, p. 27
Bushnell's basic design included some elements present in earlier experimental submersibles. The method of raising and lowering the vessel was similar to that developed by Nathaniel Simons in 1729, and the gaskets used to make watertight connections between the internal and external controls may have come from Simons, who constructed a submersible based on a 17th-century Italian design by Giovanni Alfonso Borelli.Rindskopf et al, p. 29
Preparation for use
Funding was one of Bushnell's central concerns as he planned and constructed the Turtle. Colonial records concerning the Turtle are often short and cryptic, due to efforts to keep it secret from the British, and most of the records that do exist concern Bushnell's request for funds.Royal R. "Hinman, A Historical Collection, from Official Records", Files, &c. of the Part Sustained by Connecticut, during the War of the Revolution (Hartford, Conn., 1842), pp. 343, 437, 531 Bushnell met with Connecticut Governor Jonathan Trumbull during 1771 seeking financial support. Trumbull also sent requests to George Washington and Thomas Jefferson. Jefferson was intrigued by the possibilities, while Washington remained skeptical of devoting funds from the Continental Army, whose funding was already being stretched.
Several setbacks plagued the design process. The mine in particular was delayed several times from its expected completion from 1771 to 1776. Piloting the Turtle, moreover, required great physical stamina and coordination. The operator would have to adjust the bilge in order to keep from sinking while providing propulsion by use of a crank, which worked a propeller on the front of the submarine, and simultaneously directing the submarine with a lever that operated a rudder at the back. The cabin also held air for only 30 minutes of use, after which the operator would have to surface and replenish the air through a ventilator. Training would be needed in order to ensure the project's success due to the complex nature of the machine.
"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.Milkofsky, Brenda. David Bushnell And His Revolutionary Submarine (Connecticut History.org. N.p., 2017). Bushnell did the initial testing of his submarine on the Connecticut River, choosing his brother Ezra as the pilot. In August 1776, Bushnell asked General Samuel Holden Parsons for volunteers to operate Turtle because his brother Ezra was taken ill.Abbot, Thatcher's Journal, p. 185 Three men were chosen, and the submersible was taken to Long Island Sound for training and further trials.Manstan, p. 193 While these trials went on, the British gained control of western Long Island in the August 27 Battle of Long Island, giving them control of New York harbor. Turtle was transported overland from New Rochelle to the Hudson River.
After two weeks of training, Turtle was towed to New York, and Sgt. Ezra Lee prepared to use it to attack , flagship of the blockade squadron.Manstan, p. 129 Destroying this symbol of British naval power by means of a submarine would be a blow to British morale and could threaten the British blockade and control of New York Harbor. The plan was to have Lee surface just behind Eagles rudder and use a screw to attach an explosive to the ship's hull. Lee would then dive the Turtle and make his escape.Don Walsh, 2011. "Turtle: David Bushnell's Revolutionary Vessel." Naval History 25, no. 1: 69–70. Academic Search Premier, EBSCOhost
Attack on the Eagle
At 11:00 pm on September 7, 1776, Sgt. Lee piloted the submersible toward Admiral Richard Howe's flagship , then maneuvered it out to the anchorage off Governors Island. 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. Adding to his difficulties was a fairly strong current and the darkness, which made visibility difficult.
Lee began his mission with only 20 minutes of air, and the darkness, the speed of the currents, and the added complexities all combined to thwart his plan. Once surfaced, Lee lit the fuse on the explosive and tried multiple times to stab the device into the underside of the ship, but he was not able to pierce Eagles hull. He abandoned the operation when the timer on the explosive was due to go off, and he feared getting caught at dawn. A popular story held that he failed due to the copper lining covering the ship's hull. 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. Bushnell believed that Lee's failure was probably due to an iron plate connected to the ship's rudder hinge.Schecter, p. 174 Lee attempted another spot on the hull, but he was unable to stay beneath the ship and eventually abandoned the attempt.
Lee reported that British soldiers on Governors Island spotted the submersible and rowed out to investigate. He then released the charge (called a torpedo), "expecting that they would seize that likewise, and thus all would be blown to atoms." The British were suspicious of the drifting torpedo and retreated back to the island. 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." It was the first use of a submarine to attack a ship, but the only records documenting it are American. British records contain no accounts of an attack by a submarine or any reports of explosions on the night of the attack on Eagle.Compton-Hall, pp. 32–40