The Turtle- The First Combat Submarine

7 minutes

Submarines. When most people think of submarines in combat, they think of World War I or World War II. And to be fair, World War I was the first time that submarines were widely accepted in combat. That wasn’t the first time they were used in combat, however. People have been dreaming of submarines for a long time. What better way to surprise your naval enemies than to sneak up underneath them?

Enter the Turtle:

Geni, CC BY-SA 4.0, via Wikimedia Commons

The Turtle submarine is a one-person submarine designed to allow the driver to attach bombs to the bottom of boats. It was used briefly during the American Revolutionary War, in 1776. It wasn’t until 1900 that submarines became accepted in combat, with the formation of the US Navy Submarine Force. 125 years after the first combat submarine was used. So what was the Turtle, and why was the idea abandoned for such a long time?

The Turtle Submarine’s Beginnings

David Bushnell designed the Turtle over several years while he studied at Yale. Between 1771-1775, he worked on the design. He also made prototypes of underwater explosives that would make his submarine a feasible weapon. His final design met all the requirements for a modern submarine: it could submerge completely, move independently underwater, had enough air to support the operator, and could carry out an attack against another vessel.

His designs, of course, went nowhere at first. It wasn’t until Johnathan Trumbull, the governor of Connecticut, wrote to George Washington in 1775, that Bushnell finally received the funding he needed to bring his designs to life.

Isaac Doolittle was an inventor near Yale, and ended up helping Bushnell to design and invent a good number of the brass pieces that made the Turtle work, including the oars, the hatch, and the detonator for the mine.

The Design

The Turtle was a small vessel, measuring only seven and a half feet wide, and six feet tall. Designed for a single person, it was meant to attack a nearby ship. It was not designed for any sort of long-term underwater mission. The operator of the Turtle would only have a half hour of air before having to resurface. A mine was attached to the back, filled with gunpowder. This gunpowder was Bushnell’s design as well, and could be detonated even underwater. The Turtle was to be used to sneak up on a ship, attach the mine with its’ time delayed detonator to the ship in secret, and get away again without being spotted.

It got its name from its resemblance to two tortoise shells pressed together. Dr. Benjamin Gale describes the Turtle Submarine best in a letter to Sileas Deane in November 1775:

Excerpt from Dr. Gale’s letter to Sileas Deane- November 1775

“The person who navigates it enters at the top. It has a brass top or cover, which receives the person’s head as he sits on a seat, and is fastened on the inside by screws. In this brass head is fixed eight glasses, viz. two before, two on each side, one behind, and one to look out upwards. In the same brass head are fixed two brass tubes, to admit fresh air when requisite, and a ventilator at the side to free the machine from the air rendered unfit for respiration. On the inside is fixed a Barometer, by which he can tell the depth he is underwater; a Compass, by which he knows the course he steers. In the barometer and on the needles of the compass is fixed fox-fire, i.e. wood that gives light in the dark.

His ballast consists of about 900 wt. of lead which he carried at the bottom and on the outside of the machine, part of which is so fixed as he can let run down to the Bottom, and serves as an anchor, by which he can ride ad libitum. He has a sounding lead fixed at the bow, by which he can take the depth of water under him; and to bring the machine into a perfect equilibrium with the water, he can admit so much water as is necessary, and has a forcing pump by which he can free the machine at pleasure, and can rise above water, and again immerge, as occasion requires.”

Shubol3D, CC BY-SA 4.0, via Wikimedia Commons

The Turtle Submarines’ First Mission

Once the Turtle had been built and tested, three men were chosen to train with it in the Connecticut River in secret. It was ultimately decided that Sergeant Ezra Lee would operate the Turtle on its’ first mission.

With the British controlling New York Harbor in 1776, the Turtle was directed to attack the HMS Eagle. On September 6, 1776, Lee entered the water with only 20 minutes of air, rather than the expected 30. It was night, and the dark combined with the currents made it difficult to keep the submarine on a steady course toward the ship. Lee had to surface several times over the 2-hour journey to the Eagle. He refreshed his air supplies and checked his course during his time above water.

Operating the Turtle wasn’t easy. It was not truly designed to move easily within the water. It was moved via a front propeller, which the operator had to manually spin. The interior was, of course, nearly pitch black. Any flame that could illuminate the inside would have eaten up the air within. Eventually, Lee was able to surface just behind the Eagle. Despite his best efforts, he couldn’t get the mine to attach to the ship. He was spotted by guards on Governer’s island and ended up releasing the mine to float downriver. The mine did work and produced quite the explosion. But it was nowhere near the Eagle.


The Turtle was used in two more attempted attacks, but few records remain about these attacks. Unfortunately, the Turtle Submarine was sunk when its transport ship was destroyed on October 9th, 1776. It was salvaged from the depths, but never repaired. Three unsuccessful attacks and a high repair bill meant that the original Turtle was never restored.

Submarines were used during both the war of 1812 and the American Civil War. The Confederate submarine H.L. Hunley was the first to sink a ship in battle, the Housatonic, on February 17, 1864. The H.L. Hunley never returned to port after the successful sinking of the battleship. By the early 1900’s, submarines were beginning to be more developed and built by various Navies. In WWI, the US Navy had 72 submarines in active service.

Replica of the Hunley
DrStew82, CC BY-SA 4.0, via Wikimedia Commons

The Turtle Submarine may not have been effective, but it was an important first step toward submersible craft. It showed the feasibility of underwater craft, and while it never succeeded in an attack, formed the basis for future submarines. It was the first submarine to use water and lead as a ballast for rising and sinking, and the first to use screw propellers.

Bushnell was constrained by the materials available to him, but his genius was recognized in letters from George Washington and Benjamin Franklin. The US Navy also recognized his accomplishments by naming two submarine tenders after him, once in 1915, and another in 1945.

If you want to see a replica of the Turtle, you can visit one at the Connecticut River Museum in Essex. Another replica can be found in Washinton DC, in the lobby of the International Spy Museum.

Want to read more?

Check out these links for more information about the Turtle Submarine!

Here is a link to the Wikipedia Article!

Here is a great resource- the US Naval History and Heritage Command!

The American Battlefield Trust also did a great write-up of the Turtle!

Want to Read about more Strange Inventions?

Read about the horrifying Birthing Spinner!

Or Read about Ben Franklin’s haunting musical instrument!