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Turtle (submersible)
Turtle (submersible)
from Wikipedia
A cutaway full-sized replica of the Turtle on display at the Royal Navy Submarine Museum, Gosport, UK
History
United States
NameTurtle
NamesakeTurtle
BuilderDavid Bushnell
Laid down1775 251 years ago
Launched1775
Commissioned1775
In service1775–1776
FateUnknown
General characteristics
Class & typeSubmarine or Submersible
Displacement91 kg (201 lb)
Length3.0 m (9 ft 10 in)
Beam0.9 m (2 ft 11 in)
PropulsionHand-cranked propellers
Speed2.6 kn (4.8 km/h; 3.0 mph)
Endurance30 min
NotesFirst submarine with a documented record of use in combat

Turtle (also called American Turtle) was the world's first submarine,[1] or by modern standards 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

[edit]
A diagram showing front and side views of Turtle

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.[2]

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."[3]

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.[4] According to Dr. Benjamin Gale, the many brass and mechanical parts of the submarine were built by New Haven inventor Isaac Doolittle,[5] whose shop was just half a block from Yale.[6]

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.[5] He had designed and manufactured complicated brass-wheel hall-clocks, a mahogany printing-press,[7][8] 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.[9]

This 19th-century diagram shows the side views of Turtle. It incorrectly depicts the propeller as a screw blade; it was actually a paddle propeller blade, as seen in the replica shown above and reported by Sergeant Lee.[10]

The design of the Turtle was necessarily shrouded in secrecy,[11] but Doolittle probably designed and crafted the brass and moving parts of the Turtle,[12] including the propulsion system,[13] the navigation instruments,[14] the brass foot-operated water-ballast and forcing pumps,[15] the depth gauge and compass,[16] the brass crown hatch,[17] the clockwork detonator for the mine,[18] and the hand-operated propeller crank and foot-driven treadle with flywheel.[19]

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".[20]

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.[21] Benjamin Gale described it to Silas Deane as "two oars or paddles" that were "like the arms of a windmill...twelve inches (30 cm) long, and about four (10) wide."[22] Manstan speculates that it was made of brass and was likely designed and forged by Doolittle.[23]

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.[24] The hull was "constructed of oak, somewhat like a barrel and bound by heavy wrought-iron hoops."[25] The shape of the hull, Gale informed Silas Deane, "has the nearest resemblance to the two upper shells of a Tortoise joined together."[26]

Turtle was about 10 feet (3.0 m) long (according to the original specifications), 6 feet (1.8 m) tall, and about 3 feet (0.9 m) wide, and consisted of two wooden shells covered with tar and reinforced with steel bands.[27] 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 200 pounds (91 kg) 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 3 mph (2.6 kn; 4.8 km/h).[27]

Six small pieces of thick glass in the top of the submarine provided natural light.[27] 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.[28]

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.[29]

Preparation for use

[edit]
Turtle submarine design explained

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.[30] 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.[31] 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.[32] Three men were chosen, and the submersible was taken to Long Island Sound for training and further trials.[33] 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 HMS Eagle, flagship of the blockade squadron.[34] 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 Eagle's rudder and use a screw to attach an explosive to the ship's hull. Lee would then submerge and make his escape.[35]

Attack on the Eagle

[edit]
Portrait of Ezra Lee, Turtle's operator

At 11:00 pm on September 7, 1776, Sgt. Lee piloted the submersible toward Admiral Richard Howe's flagship HMS Eagle, 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 Eagle's 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.[36] 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."[36] 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."[36] It was the first use of a submarine to attack a ship,[29] 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.[37]

British naval historian Richard Compton-Hall has questioned whether these events even occurred. He claims that the problems of achieving neutral buoyancy would have rendered the vertical propeller useless. The route that Turtle would have taken to attack Eagle was slightly across the tidal stream which would have likely resulted in Lee becoming exhausted.[37] In the face of these and other problems, Compton-Hall suggests that 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.[37]

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. He laboured for some time ineffectually and, though the advocates for his scheme continued sanguine, he never did succeed. One accident or another was always intervening. I then thought, and still think, that it was an effort of genius; but that a combination of too many things were requisite."[38]

Turtle's attack on Eagle reflected both the ingenuity of American forces after the fall of New York and the American tendency to embrace new, sometimes radical, technologies. "What astonishment it will produce and what advantages may be made… if it succeeds, 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.

Aftermath

[edit]
Bushnell mines destroying a small British boat

On October 5, Sergeant Lee again went out in an attempt to attach the charge to a frigate anchored off Manhattan. He reported the ship's watch spotted him, so he abandoned the attempt.

Turtle was lost on October 9, 1776, while aboard the sloop serving as her tender when the Royal Navy frigates HMS Phoenix, HMS Roebuck, and HMS Tartar sank the sloop by gunfire in the Hudson River near Fort Washington on Manhattan[39] and Fort Lee, New Jersey. Bushnell reported salvaging Turtle, but its final fate is unknown.[40] Washington called the attempt "an effort of genius", but "a combination of too many things was requisite" for such an attempt to succeed.[41]

Following Turtle's abortive attack in New York Harbor, Bushnell continued his work in underwater explosives. In 1777, he devised mines to be towed for an attack on HMS Cerberus near New London harbor[42] and to be floated down the Delaware River in an attempt to interrupt the British fleet off Philadelphia.[43] Both attempts failed; On August 13, 1777, a Bushnell floating mine/keg sank a small (captured) schooner/tender to HMS Cerberus, in Black Point Bay, New London, CT killing three sailors and saving 1 man.[44] Regarding the floating mines; the only casualties were two curious young boys who were killed by a mine/keg and alerting the British.[45] The latter attempt occupied a brief, if farcical, place in the literature of the war. Francis Hopkinson's poem "Battle of the Kegs," captured the surprising, if futile, venture: "The soldier flew, the sailor too, and, scared almost to death, sir, wore out their shoes to spread the news, and ran till out of breath, sir."

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.[46] After the war, Bushnell drifted into obscurity. He visited France for several years, then moved to Georgia in 1795 under the assumed name of David Bush, where he taught school and practiced medicine. He died largely unknown in Georgia in 1824. After the war, inventors such as Robert Fulton were influenced by Bushnell's designs in the development of underwater explosives.[citation needed]

Replicas

[edit]

The Turtle was the first submarine used for combat and led to the development of what we know today as the modern submarine, forever changing underwater warfare and the face of naval warfare. As such, the Turtle has been replicated many times to show new audience the roots of submarine technology, how much it has changed, and the influence it has had on modern submarines. By the 1950s, historian of technology Brooke Hindle credited the Turtle as "the greatest of the wartime inventions."[47] 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. As Benjamin Gale noted in 1775, the vessel was "constructed with great simplicity," and it has thus inspired at least four replicas.[48] Many of these followed the designs set down by Bushnell, with "precise and comprehensive descriptions of his submarine," which aided the replication process.[49]

The vessel was a source of particular pride in 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. It was christened by Connecticut's governor, Ella Grasso, and later tested in the Connecticut River. This replica is owned by the Connecticut River Museum.

In 2002, Rick and Laura Brown, two sculptors from Massachusetts, along with Massachusetts College of Art and Design students and faculty, constructed another replica. The Browns set out to gain a better understanding of human ingenuity while keeping Bushnell's design, materials, and technique authentic. "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. Of the temptation to use synthetic and ahistorical materials, Rob Duarte, a MassArts student observed, "It was always a temptation to use silicone to seal the thing. Then you realized that someone else had to figure this out with the same limited resources that we were using. That's just an interesting way to learn. You can't do it any other way than by actually doing it." The outer shell of the replica was hollowed, using controlled fire, from a 12-foot (3.7 m) Sitka spruce. The log was 7 feet (2.1 m) in diameter and shipped from British Columbia. This replica took twelve days to build and was successfully submerged in water. In 2003, it was tested in an indoor test tank at the United States Naval Academy. Lew Nuckols, a professor of Ocean Engineering at USNA, made ten dives, noting "you feel very isolated from the outside world. If you had any sense of claustrophobia it would not be a very good experience."[50] The replica is currently on display at the International Spy Museum in Washington, DC.[51]

In 2003, Roy Manstan, Fred Frese, and the Naval Underwater Warfare Center partnered with students from Old Saybrook High School in Connecticut on a four-year project called The Turtle Project, to construct their own working replica, which they completed and launched in 2007.[52][53]

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. Riley claimed that he wanted to film himself next to the Queen Mary 2 for his upcoming gallery show. Riley's was not an exact replica, however, measuring 8 feet (2.4 m) tall and made of cheap plywood then coated with fiberglass. Its portholes and hatch were collected from a marine salvage company. He also installed pumps to allow him to add or remove water for ballast. Riley christened his vessel Acorn, to note the deviation from Bushnell's original design. The vessel, reported the New York Times, "resembled something out of Jules Verne by way of Huck Finn, manned by cast members from 'Jackass.' The Coast Guard issued Riley a citation for having an unsafe vessel, and for violating the security zone around Queen Mary 2. The NYPD also impounded the submarine. 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.[54]

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.[55][56] The submarine was shipped to Richmond, where it underwent a full refit and was relaunched for film use in the water. Additional full-scale interior and exterior models were also made by AMC as part of the production.

Also in 2015, Privateer Media used The Turtle Project replica for the Travel Channel series Follow Your Past, hosted by Alison Stewart. Filming took place in August where the submarine was launched with a tether in the Connecticut River in the town of Essex, CT.

Footnotes

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
The Turtle was a one-man wooden invented by American David Bushnell in 1775 and employed by Continental forces during the as the world's first submarine used in combat. Resembling two joined shells, the vessel measured approximately seven and a half feet in length and six feet in height, constructed in , with assistance from Bushnell's brother Ezra. It submerged by admitting water into bilges for ballast and surfaced via manual pumps, navigated using hand- and foot-cranked screw propellers—the first such underwater propulsion system—and illuminated internally by phosphorescent "." Bushnell equipped the Turtle with an explosive "torpedo"—an egg-shaped mine containing up to 150 pounds of gunpowder and a clockwork detonator—intended to be drilled into enemy hulls for attachment. On September 6–7, 1776, operator Ezra Lee attempted to target the British flagship HMS Eagle in New York Harbor, but the mission failed when the drill could not penetrate the ship's copper sheathing; subsequent efforts that month and in October also aborted due to currents, operator fatigue, and technical issues. The submersible was ultimately sunk by British fire in the Hudson River but recovered without further successful deployments, though Bushnell's innovations in submersible propulsion, ballast control, and contact mines laid foundational principles for modern naval warfare.

Historical Context

The Royal entered the with overwhelming superiority, possessing approximately 270 warships in 1776 compared to the Continental Navy's mere 27 vessels. This disparity in numbers, combined with British crews' superior , gunnery, and tactical aggression, enabled the Royal Navy to dominate maritime operations, including amphibious support for ground forces and enforcement of blockades that crippled colonial trade and supply lines. Britain's prioritized control of key coastal ports to isolate rebel armies and economies, leveraging global shipbuilding capacity to maintain fleet strength despite European distractions. The Continental Navy, established by on October 13, 1775, played a limited role due to its small size—peaking at 31 vessels by —and lack of heavy warships capable of challenging British squadrons. American maritime efforts instead relied heavily on over 2,000 privateers commissioned across the colonies, which focused on rather than fleet engagements, capturing hundreds of British merchant vessels but failing to contest naval supremacy. State navies and riverine forces supplemented this, but colonial shipyards produced few ocean-going combatants, leaving harbors vulnerable to uncontested British incursions. In 1776, this imbalance manifested acutely during the New York campaign, where Admiral Richard Howe's fleet of over 30 warships arrived in July, facilitating the transport of 32,000 troops and imposing a de facto blockade on the harbor after the British victory at the on August 27. had anticipated such a blockade, recognizing its potential to sever New York from allied support and strangle Continental communications along the . Anchored British flagships, including HMS Eagle, became symbols of this dominance, prompting unconventional American innovations like submersible attacks to target them at rest, as direct confrontation remained infeasible.

Design and Construction

Invention and Development

David Bushnell, born August 8, 1742, in (now Westbrook), pursued formal education later in life, enrolling at around 1771 after working as a farmer and displaying an aptitude for and explosives experimentation. While studying and there, Bushnell conceived the Turtle submersible in 1775 as a response to the American colonies' need for innovative naval tactics against the superior British fleet during the Revolutionary War, aiming to deliver underwater explosives without surface exposure. Construction commenced in early 1775 under Bushnell's direction, with assistance from his brother Ezra Bushnell for the hull and local and Isaac Doolittle for the internal mechanisms, including hand-cranked propellers and valves; shipwright Phineas Pratt contributed to the time-keeping devices for underwater navigation. The ovoid vessel, resembling a , was fashioned from a single large log sawn in half and hollowed, reinforced with iron hoops, and sealed with tarred and salvaged or plating to achieve waterproofing, measuring approximately 7.5 feet long and 3 feet wide. The Turtle incorporated pioneering features such as water ballast tanks for submersion—filled and emptied via hand pumps—and dual screw propellers for propulsion and depth adjustment, powered by the operator's foot and hand cranks, enabling travel at about 1.5 knots submerged for up to 30 minutes before resurfacing for air. Initial trials in the near Saybrook in late 1775 confirmed basic functionality, including submersion to 20 feet and horizontal movement, though Bushnell's personal attempts revealed challenges with operator endurance and equilibrium due to his susceptibility to . Parallel development focused on the explosive delivery system: a wooden keg-shaped "" containing 100 to 150 pounds of black , fitted with a igniter triggered by a or drill auger to pierce a ship's copper-sheathed hull for attachment. This mine, tested successfully against stationary targets, represented Bushnell's prior work on floating gunpowder kegs, refined for deployment to enhance stealth and reliability against moving vessels.

Technical Specifications and Innovations

The Turtle submersible, constructed primarily from oak timbers six inches thick, was reinforced with iron bands and coated in tar for waterproofing, forming a pear-shaped hull resembling two joined shells. Its dimensions measured approximately 7.5 feet in length and 6 feet in height, with an elliptical hatch secured by screws providing access for the single operator. The vessel incorporated 900 pounds of lead ballast, including 200 pounds detachable for emergency surfacing, and featured eight glass-paned windows for visibility. Propulsion relied on a hand-cranked or foot-treadle-operated screw , approximately 12 inches long and 4 inches broad, enabling forward and backward motion at speeds up to 3 knots in short bursts, though typically around 2 knots. A vertical or auxiliary mechanism assisted in depth adjustments, marking the first use of a screw in a for underwater maneuverability. Diving was achieved by admitting through a foot-operated into the hull, functioning as a primitive ballast system, with two brass force pumps used to expel water for ascent; a barometer-like with a phosphorus-illuminated cork float aided submersion control to depths of about 20 feet. Innovations included an early system with two valved pipes and a , providing roughly 30 minutes of breathable air, supplemented by manual if needed. The armament consisted of a detachable "torpedo"—an egg-shaped containing 150 pounds of , armed with a fuse and attached to enemy hulls via a hand-turned auger or woodscrew , representing the first attempt at submersible-delivered explosive ordnance. These features established foundational principles for , including controlled submergence via water ballast and mechanical propulsion independent of surface effects, despite the operator's physical exertion limiting endurance.
Key SpecificationsDescription
Hull Material, iron-reinforced, tarred
Dimensions~7.5 ft length × 6 ft height
Ballast900 lbs lead (200 lbs detachable)
Propulsion Speed2–3 knots
Air Supply Duration~30 minutes
Armament150 lbs time bomb

Construction Challenges

The Turtle's hull presented formidable construction challenges due to the need for a pressure-resistant, watertight enclosure using rudimentary materials available in 1775 colonial America. Crafted from timbers approximately six inches thick, the barrel-shaped measured about seven and a half feet in diameter and height, reinforced externally with heavy wrought-iron hoops to counter compressive forces underwater. Sealing the wooden joints against water ingress required meticulous caulking followed by a coating of pitch or , a process complicated by wood's natural expansion and contraction under varying humidity and pressure, with no established precedents for applications. Fabricating the internal mechanisms demanded specialized artisanal skills scarce amid wartime disruptions. Inventor David Bushnell enlisted machinist Isaac Doolittle to produce the hand-operated for management—allowing water intake via bottom valves for submergence and expulsion for ascent—and the airtight hatch, whose multi-layered design with screw-tightening seals proved the most intricate component to assemble without compromising integrity. The propulsion apparatus, comprising a horizontal screw for forward motion and a vertical one for depth adjustment, both driven by foot treadles and hand cranks linked to gears, required precise alignment to generate sufficient thrust from human power alone, estimated at two knots maximum, while integrating 700 pounds of lead for stability. Additional hurdles arose from the novelty of the design and logistical constraints. Ventilation systems, including two snorkel tubes with self-closing valves to maintain air supply for roughly 30 minutes of submersion, had to be engineered to exclude water while permitting operator respiration, a feat untested in prior diving devices. proceeded in secrecy at , to evade British intelligence, which limited access to materials and prolonged the timeline; initial plans for deployment against the blockade were thwarted as completion extended into , shifting focus to . These efforts underscored the empirical trial-and-error inherent in pioneering , reliant on Bushnell's first-hand experimentation rather than formalized theory.

Operational History

Preparation and Crew Training

Following construction in , in late 1775, the Turtle underwent testing and minor alterations to prepare for operational use, including adjustments over approximately ten days prior to its first mission attempt in September 1776. Initially intended to be piloted by inventor David Bushnell's brother, Ezra Bushnell, who had received about a year of training, the vessel's deployment was delayed when he fell seriously ill with fever on the eve of the operation. To address this, Brigadier General Samuel Holden Parsons provided three volunteers from the Continental Army, whom David Bushnell trained in the operation of the submersible. Sergeant Ezra Lee, a 27-year-old from , demonstrated the greatest aptitude among the trainees and was selected as the pilot. Training occurred over two weeks in the Saybrook area along the coast, relocated northward from initial sites to maintain secrecy and evade potential British detection. During this period, Lee learned to maneuver the single-person vessel, which required physical exertion to operate its hand-cranked propeller and manage for submergence and resurfacing, though he encountered challenges such as strong tidal currents that tested the submersible's handling. After training, the Turtle was transported southward to the New York Harbor vicinity for deployment against the British fleet, initially towed into position on the night of September 6, 1776. The preparation emphasized the vessel's novel mechanisms, including its water ballast system for diving—the first such use in a submersible—and the attachment of a mine loaded with gunpowder, but no additional crew beyond the pilot was involved, reflecting the design's limitation to solo operation.

Primary Attack on HMS Eagle

![Portrait of Ezra Lee, pilot of the Turtle][float-right] Sergeant Ezra Lee of the Continental Army piloted the Turtle submersible in its first combat mission against the British flagship HMS Eagle on the night of September 6–7, 1776, in . The Eagle, a 64-gun serving as Howe's command vessel, was anchored off as the primary target selected by General to disrupt British naval operations. Lee departed from the schooner General Putnam around 11:00 p.m. on September 6, propelled by hand-cranked screws after being towed into position, navigating submerged or partially submerged to evade detection. Upon reaching the Eagle shortly after midnight, Lee maneuvered the Turtle beneath the hull and attempted to affix a detachable mine containing approximately 150 pounds of using a screw auger designed to into the ship's planking. The auger failed to penetrate, likely due to the Eagle's —installed to deter marine growth and worms—or a blunt exacerbated by the vessel's reinforced construction, preventing the mine from being secured despite multiple efforts. Hearing the sounds of British oarsmen nearby, Lee, low on air and facing rising tension, detached the mine to avoid recapture, allowing it to surface and drift away with its clockwork fuse ticking. The mine exploded harmlessly in the harbor around dawn on , alerting British forces but causing no damage or casualties. Lee resurfaced the Turtle and pedaled back to friendly lines undetected, completing the world's first documented submarine attack, though unsuccessful in its objective. The mission highlighted the Turtle's potential for stealthy approach but exposed limitations in its attachment mechanism against contemporary protections.

Subsequent Mission Attempts

Following the unsuccessful attack on on September 7, 1776, Sergeant Ezra Lee conducted another mission in October 1776 targeting a British frigate off Bloomingdale in the North River. The operation failed after Lee was detected by the ship's watch; a cork lodged in the tube caused the Turtle to descend excessively, disorienting the operator and preventing reorientation toward the hull. Lee attempted a third mission later that October in the above . Strong tidal currents swept the Turtle away, causing loss of visual contact with the target vessel and rendering attachment of the explosive impossible. On October 9, 1776, British gunfire sank the Turtle during an attempted recovery, though it was later salvaged by American forces. No further operational missions occurred, as persistent issues with operator proficiency, navigation, and environmental factors—compounded by British naval repositioning—precluded additional viable attacks.

Failures and Aftermath

Technical and Operational Shortcomings

The Turtle submersible encountered numerous technical limitations that undermined its , primarily stemming from its rudimentary one-man and manual mechanisms. Propulsion relied on hand-cranked horizontal and vertical screws, enabling a maximum speed of 2-3 knots but demanding intense physical effort from the operator, limiting operational to approximately 30 minutes before set in. This exhaustion was exacerbated during the , 1776, attempt against HMS Eagle, where operator Ezra Lee reported physical strain compounded by oxygen depletion in the confined space. A critical shortcoming was the mine attachment system, which featured a hand-driven wood screw on a vertical shaft intended to bore into an enemy hull and secure a 150-pound magazine with clockwork fuse. During the Eagle mission, the mechanism failed to penetrate the target's iron strapping or , preventing securement despite multiple attempts; Lee struck unyielding metal both times, forcing him to release the mine prematurely, which detonated harmlessly nearby. , applied to British ships to deter marine fouling, inadvertently thwarted the drill's efficacy, highlighting a oversight in anticipating hull reinforcements. Buoyancy and depth control proved unreliable, managed via foot-operated flood valves, hand pumps for water, and a 200-pound releasable lead weight to avert permanent submergence. The primitive —a sealed tube with a floating cork illuminated by —offered imprecise readings, contributing to instability and "porpoising" oscillations during dives, as operators overcorrected manually under stress. Navigation further complicated operations, with no or external visibility; reliance on a phosphorescent and tidal feel was disrupted by strong harbor currents, such as those in , which repeatedly carried the craft off course and hindered repositioning beneath targets. Insufficient crew training amplified these issues, as noted by , who described the Turtle as "an effort of genius; but too many things were necessary to be combined to succeed." Subsequent missions on the in 1776 yielded similar fruitless results due to these interconnected flaws.

Destruction and Immediate Consequences

Following the unsuccessful attempts to deploy the Turtle against British shipping in the after the September 7, 1776, attack on , the submersible was loaded onto an American for transport northward as Continental forces retreated from advancing British troops. During the Battle of Fort Lee on November 20, 1776, British forces under Lord Cornwallis captured the area, and the sloop transporting the was sunk, resulting in of the vessel to the riverbed. Although David Bushnell later claimed to have recovered the craft, contemporary accounts and historical analyses indicate it was irretrievably damaged or abandoned, with its precise fate remaining unverified due to wartime chaos and lack of salvage records. The immediate consequence was the termination of the Turtle project, as no operational submersible remained for further missions amid the British occupation of New York and the Hudson Valley. Bushnell, recognizing the insurmountable operational challenges—including unreliable propulsion, pilot endurance limits, and attachment mechanism failures—redirected efforts to alternative weapons, such as manually deployed floating mines (known as "torpedoes") tested later in 1777 against British vessels like HMS Cerberus. General , who had supported the initiative, acknowledged the innovative intent but highlighted practical deficiencies in correspondence, effectively ending submarine experimentation within the Continental forces at that stage. The loss underscored the era's technological constraints, with no immediate British reprisal specifically targeting submersible threats, though it contributed to heightened vigilance around anchored ships post-Eagle incident.

Legacy and Impact

Influence on Future Submarine Technology

The Turtle's innovations in , including the use of water admitted through valves to achieve negative for submergence and expelled for positive to surface, established a core principle of hydrostatic control that persisted in subsequent engineering. Its dual hand-cranked propellers—one for forward and one for vertical movement—provided the first documented instance of independent underwater maneuvering without reliance on surface tow or sails, addressing the challenge of in a submerged state. These mechanical solutions, powered by human effort via geared screws, demonstrated the potential for directed subaquatic navigation, though limited by the operator's endurance to approximately 30 minutes of sustained operation at depths up to 20 feet. American inventor drew directly from Bushnell's concepts in developing the , launched in 1800, which incorporated a similar hand-cranked screw propeller for and refined ballast systems for depth control, enlarging and adapting the 's one-man ovoid hull into a copper-sheathed vessel capable of greater endurance and delivery. Fulton's design echoed the 's essentials, such as a retractable air pipe for ventilation and an auger mechanism for hull attachment, though he shifted toward sail-assisted surface travel and later experimented with hand-pumped air compression to extend dive times beyond the 's constraints. This progression marked the as a influencing early 19th-century experiments, including Fulton's demonstrations for French and American navies, which tested submerged attacks against anchored targets. Over the long term, the Turtle's emphasis on covert underwater approach and explosive ordnance delivery contributed to the conceptual evolution of submarine warfare, inspiring Civil War-era Confederate designs like the H.L. Hunley (1864), which adopted crew-powered propulsion and spar torpedoes akin to Bushnell's drill-auger method, albeit with a multi-man crew to distribute cranking fatigue. While modern nuclear and diesel-electric submarines diverged technically—replacing manual cranks with engines and adopting hydroplanes for precise depth control—the foundational ideas of ballast-induced submergence and propeller-driven independence underwater remain integral, as evidenced by their continuity in designs from the 1880s onward. The Turtle's legacy thus lies less in immediate technical adoption, given its operational unreliability against copper-sheathed hulls, and more in validating the viability of submersible tactics against surface fleets.

Historical Recognition

The United States Navy acknowledges the Turtle as the first submersible employed in combat, crediting David Bushnell with pioneering innovations such as water ballast for submergence and a hand-cranked screw propeller for underwater propulsion. This recognition underscores the Turtle's role as a prototype for modern submarines, despite its operational failures. In tribute to Bushnell's contributions, the U.S. Navy named two submarine tenders after him: one commissioned during in 1915 and another during . The Submarine Force Library and Museum in , maintains a detailed exhibit and cutaway replica of the Turtle, highlighting its historical significance in naval innovation. Historical societies have also commemorated Bushnell and the Turtle through monuments, including a cenotaph erected by the Atlanta Chapter of the Sons of the American Revolution to honor the inventor as a Revolutionary War patriot. Scholarly works, such as those published in the U.S. Naval Institute Proceedings, affirm the Turtle's launch in 1775 at Old Saybrook, Connecticut, as the inception of submarine warfare tactics. These acknowledgments emphasize empirical advancements in underwater navigation and ordnance delivery, evaluated through primary accounts from the era rather than later reinterpretations.

Replicas and Modern Reconstructions

Early 20th-Century Replicas

In the early , no full-scale replicas of David Bushnell's Turtle submersible were constructed, as historical interest focused primarily on textual accounts, diagrams, and small-scale models for rather than operational recreations. The U.S. honored Bushnell's innovation indirectly through ship namings, such as the submarine tender USS Bushnell (AS-2) commissioned in 1915 and its successor in 1945, but these did not involve physical replicas of the original vessel. Full-scale efforts awaited later commemorations, with the first functional replica designed by Joseph Leary and built by Fred Frese in 1976 for the American Bicentennial, now housed at the Connecticut River Museum in Essex. This absence underscores the technological and material challenges of replicating an 18th-century wooden submersible amid evolving modern submarine designs during the period.

Contemporary Builds and Testing

In 2003, Handshouse Studio, collaborating with midshipmen from the U.S. Naval Academy, constructed a functional wooden replica of the Turtle using period-appropriate materials and techniques to replicate Bushnell's process. The vessel underwent initial unmanned water tests in Duxbury Harbor, , on January 9 and 10, verifying watertightness and operational integrity of components such as the hand-cranked and system. Subsequent manned trials at the Naval Academy in Annapolis reached submersion depths of about 20 feet (6 meters), confirming stability and maneuverability in calm waters, though pedal propulsion proved physically demanding for operators sustaining speeds under 1 . Another functional replica was built in 2007 by high school students in , facilitated by the Friends of the Submarine Fleet Obsolete Submarines Association (FOSA-CT) as an educational project to test Bushnell's empirically. Launched in November 2007 into the near the site's original 1775 test location, it underwent operational evaluations at Museum, including submersion, propulsion, and navigation trials under expert submariner oversight. These tests yielded data on handling, estimating the original Turtle's maximum pilot-sustainable speed at 1 against currents and highlighting limitations in visibility and depth control without modern aids. In the same year, artist Philip "Duke" Riley crafted a replica for a reenactment of the 1776 mission, launching it from on August 3, 2007, toward the docked RMS Queen Mary 2 in . Riley piloted the craft submerged for portions of the approach, demonstrating basic functionality before interception by U.S. and harbor police vessels; no attack mechanism was deployed, but the incident underscored contemporary protocols treating unauthorized submersibles as potential threats.

References

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