The Bushnell Turtle Was The World’s First Submarine

The Bushnell Turtle was the first documented submarine used in combat, designed by David Bushnell during the American Revolutionary War.

Despite its innovative design and stealth capabilities, it faced significant operational challenges, which led to its eventual failure to successfully attack any British ships.

The Turtle’s pioneering use of submersible technology laid the groundwork for future advancements in submarine warfare.


Historical Background

The Bushnell Turtle emerged during a crucial period in the American Revolutionary War, a conflict marked by the colonists’ struggle for independence from British rule. The war began in 1775, fueled by growing dissatisfaction among the American colonists with British policies, including taxation without representation and oppressive governance.

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The colonists faced a formidable opponent in the British Empire, which boasted one of the most powerful and technologically advanced navies in the world. Control of the seas was a critical strategic advantage for the British, allowing them to transport troops, blockade ports, and disrupt American supply lines with relative ease.

A cutaway, showing the design and layout of the Turtle.
A cutaway, showing the design and layout of the Turtle.

In this challenging context, the American forces, lacking a comparable navy, needed innovative solutions to counter British maritime dominance. The idea of using submersible vessels to conduct stealth attacks on British ships was particularly appealing because it offered a way to neutralize this advantage without requiring a large fleet or extensive resources.

David Bushnell, a recent Yale graduate and an ardent patriot, was motivated by this dire strategic situation. He believed that technological innovation could provide a decisive edge in the struggle for independence. While at Yale, Bushnell had experimented with underwater explosives, successfully detonating gunpowder under water. This experimentation laid the foundation for his development of the Turtle.

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Bushnell envisioned a small, submersible craft that could approach enemy ships undetected, attach an explosive device to their hulls, and retreat to a safe distance before detonation. This concept was revolutionary for its time, introducing the idea of underwater sabotage as a viable military tactic. The potential impact of such a vessel was immense: a successful attack could sink or severely damage a British warship, thereby disrupting their operations and boosting American morale.

Design of the Turtle

The design and construction of the Bushnell Turtle were remarkable achievements of engineering ingenuity, especially considering the technological limitations of the 18th century. The Turtle was conceived as a submersible vessel that could approach enemy ships undetected and deliver explosive charges. This necessitated a design that was both compact and functional, capable of withstanding the pressures of underwater navigation and providing a means of propulsion and control for its operator.

A replica of the Turtle is on display at the Royal Navy Museum in Gosport.
A replica of the Turtle is on display at the Royal Navy Museum in Gosport. Image by Geni CC BY-SA 4.0

The Turtle was named for its shape, which resembled a large, upright turtle. The vessel was egg-shaped, a form that contributed to its stability underwater. It measured about seven and a half feet in length, six feet in height, and three feet in width, making it small enough to be operated by a single person. The compact size was essential for stealth, allowing it to approach enemy ships without being easily detected.

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Constructed primarily from wood, the Turtle’s hull was made from thick oak, a material chosen for its strength and buoyancy. The wooden planks were banded together with iron hoops to reinforce the structure and ensure it could withstand underwater pressure. The seams between the planks were sealed with a mixture of tar and pitch to make the vessel watertight.


One of the most innovative features of the Turtle was its method of propulsion. The submarine was manually operated, with the pilot using hand-cranked propellers for both horizontal and vertical movement. A horizontal propeller, positioned at the rear, provided forward motion, while a vertical propeller, located at the top, allowed for ascent and descent. These propellers were operated by turning a crank, which was connected to a system of gears. This design enabled the Turtle to move relatively quietly through the water, maintaining the element of surprise.

A great image showing the layout of the Turtle and all of the components.
A great image showing the layout of the Turtle and all of the components. Image by Shubol3D CC BY-SA 4.0

Buoyancy control was another critical aspect of the Turtle’s design. To submerge the vessel, the operator could take on water into ballast tanks located in the lower part of the submarine. This increased the Turtle’s weight and caused it to sink. To resurface, the operator used a hand-operated pump to expel water from the ballast tanks, decreasing the vessel’s weight and allowing it to rise. Lead ballast weights could also be jettisoned in an emergency to achieve rapid ascent.

The Turtle was equipped with a rudimentary breathing apparatus, consisting of a wooden snorkel with leather valves, which allowed the operator to draw fresh air from above the water’s surface. The snorkel was essential for extended underwater operations, enabling the pilot to remain submerged for up to 30 minutes at a time.

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For navigation and observation, the Turtle had small portholes fitted with thick glass, allowing the pilot to see outside the vessel. These portholes were strategically placed to provide a view of the surroundings while minimizing the risk of water ingress.

The Turtle’s Offensive Capability

The Turtle’s offensive capability was centered around an innovative explosive device. The submarine carried a keg of gunpowder attached to its exterior by a screw mechanism. The plan was for the operator to maneuver the Turtle beneath an enemy ship, use the screw to attach the keg to the ship’s hull, and then retreat to a safe distance before detonating the charge. The explosive device was equipped with a timed fuse, allowing the operator to set it and leave before the explosion occurred.

A replica of Bushnell's Turtle on display at the U.S. Navy Submarine Force Museum and Library, Groton CT.
A replica of Bushnell’s Turtle on display at the U.S. Navy Submarine Force Museum and Library, Groton CT. Image Divemasterking2000 CC BY 2.0

This method of attack was groundbreaking, as it introduced the concept of underwater sabotage and prefigured modern naval mines and torpedoes. However, the screw mechanism required significant physical effort and precision to operate, which proved to be a challenge in the heat of combat.

The Turtle Vs HMS Eagle

The Bushnell Turtle’s most famous mission occurred on the night of September 6, 1776, during a daring attempt to strike a blow against the British naval forces stationed in New York Harbor. This operation marked the first use of a submarine in warfare.

The target of this audacious mission was the HMS Eagle, a 64-gun British warship that served as the flagship of Admiral Richard Howe. The Eagle was anchored among a fleet of British ships, posing a formidable challenge for any conventional attack. However, the Turtle’s unique design and stealth capabilities offered a novel approach to neutralizing this threat.

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Sergeant Ezra Lee, a member of the Continental Army, was selected to pilot the Turtle for this mission. Lee had undergone training with David Bushnell to familiarize himself with the operation of the submarine, including its propulsion, buoyancy control, and the mechanics of the explosive device. Despite the extensive preparation, the mission was fraught with inherent risks due to the experimental nature of the vessel and the hostile environment.

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On the night of the attack, Lee embarked on the mission from a launch point on the Manhattan shore. As he navigated the Turtle toward the British fleet, he relied on the cover of darkness to avoid detection. The journey was physically demanding, requiring Lee to continuously operate the hand-cranked propellers to propel the submarine forward. Moreover, the strong currents of the East River added to the difficulty of maintaining a steady course.

Upon reaching the vicinity of the HMS Eagle, Lee maneuvered the Turtle beneath the warship’s hull. The plan was to attach the Turtle’s explosive charge to the ship’s underside using a screw mechanism designed to bore into the hull.

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However, Lee encountered unexpected difficulties when the screw failed to penetrate the copper sheathing that protected the Eagle’s hull. This copper plating, a common feature on British ships to prevent shipworm damage, proved to be a significant obstacle. Some sources claim that Lee should have been able to penetrate the copper sheathing with ease, leading to theories that he was actually positioned below an iron plate on the ship’s rudder frame.

Turtle on display in Monaco.
The conditions inside the Turtle look brutal! Image by Zenit CC BY-SA 3.0

Despite repeated attempts, Lee was unable to secure the explosive device to the ship. The physical exertion, combined with the lack of adequate oxygen inside the Turtle, made the situation increasingly precarious. Furthermore, the challenge of working in near-total darkness under the water added to the complexity of the task.

As dawn approached and the risk of detection increased, Lee decided to abandon the mission. He detached the explosive charge, which floated away harmlessly, and began the arduous journey back to the American lines. The Turtle narrowly avoided detection by the British, thanks in part to its small size and the confusion of the early morning hours. Lee and the Turtle were successfully recovered, though the mission had failed to damage the Eagle.

The Loss of the Turtle

Following the unsuccessful attack on the HMS Eagle, David Bushnell and his team, including Sergeant Ezra Lee, attempted another mission with the Turtle off Manhattan. The target was again a British ship, but this operation faced numerous challenges. Strong currents, mechanical difficulties, and the risk of detection made the mission extremely difficult.

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After being spotted by the British ship, the mission was aborted.

The final operational challenge for the Turtle came in October, 1776. During the British attack on Fort Lee, New Jersey, the American forces were forced to retreat hastily. In the chaos of the retreat, much of their equipment, including the Turtle, was abandoned.

Reports suggest that the Turtle was either deliberately scuttled by the American forces to prevent it from falling into British hands or destroyed by the British forces when they sank the sloop which was serving as the Turtle’s tender.

The exact fate of the Turtle remains somewhat unclear, but it is generally believed that it did not survive the retreat from Fort Lee.