Experiments in Submarine Warfare during the Revolutionary War

Date: September 6–7, 1776

Location: New York

Principal commanders:American, Major General Israel Putnam (1718–1790), Sergeant Ezra Lee; British, Admiral Richard Howe (1726–1799)

Result: Technology was driven and advanced by the need to succeed in revolutionary combat.

David Bushnell was known throughout his native Connecticut for his inventive mind. While on his father’s farm, he had developed a harrow with flexible teeth, which farmers could use in the stony New England fields without the teeth’s breaking constantly. As a student at Yale College, he became interested in the possibilities of exploding kegs of black powder under water. Traditional theories of the time held that such an explosion would not work, because the water would dissipate its force. Through experiments, Bushnell proved that this theory was wrong and developed the forerunner of the naval mine.

Birth of the Turtle

With the onset of the American Revolution, Bushnell decided that his mine would be useful against the blockading British fleet, but he needed an accurate method of placing his explosives under a ship’s keel without being seen by naval gunners. His solution was a submarine vessel called the Turtle, which he designed early in 1775 while still a student at Yale. During the college’s spring vacation that year, Bushnell went home to Saybrook, Connecticut, where he and his brother Ezra spent more than a month constructing the world’s first submarine. They built no model; the Turtle was built full-sized from the start.

According to its inventor, the submarine “bore some resemblance to two upper tortoise shells of equal size joined together.” The boat was seven and a half feet long, four feet wide, and eight feet deep. Made of carefully fitted oak timbers caulked with cork and tar, Bushnell’s craft was driven by a screw propeller, the first one ever used to power a ship. The contraption included a short, primitive “snorkel,” through which the one-person crew could obtain fresh air. The tube was equipped with valves that automatically closed when the submarine submerged to greater depths. The operator navigated the vessel by looking through a glass conning tower and by checking his compass and depth gauge, which were illuminated by fox fire.

Although many accounts of David Bushnell and his Turtle do not indicate that he piloted the vessel, Robert F. Burgess in Ships Beneath the Sea (1975) reveals that he did. Once Bushnell graduated from Yale in June, 1775, he returned to Saybrook to make some adjustments to the boat. The maiden voyage of the Turtle took place in Long Island Sound, where David Bushnell stayed submerged for a rather uneventful forty-five minutes. He nearly fainted, however, and based on this initial experience, realized he was not physically capable of piloting the submarine for extended periods. From then on, his brother, Ezra, practiced maneuvering the Turtle in the sound and prepared for its ultimate mission.

In subsequent months, several devices were added to assist in navigation, including a compass and a barometer. At this point, Dr. Benjamin Gale, a family friend of the Bushnells, brought Benjamin Franklin to see the Turtle. Franklin encouraged Bushnell to take his vessel to New York, where the British fleet had set up a blockade. Franklin then told General George Washington about the submarine. Washington was doubtful, however, about the boat’s potential in his endeavors.

Demonstration of the Turtle

Through the influence of Governor Jonathan Trumbull of Connecticut in late 1775, Bushnell demonstrated the Turtle for Major General Israel Putnam of the new Continental army. Putnam was impressed and secured government financing for further development of the submarine. The army wanted to use the submersible to break the British blockade of Boston, but the British squadron departed before Bushnell could fully assemble the ballast pumps.

The next opportunity to strike at the British fleet was in 1776 at New York City. The Turtle was hauled overland and launched into the harbor from Manhattan Island. Ezra Bushnell was to have navigated the submarine in its first real combat mission; he was well prepared after a year’s training in the sound. Unfortunately, he became seriously ill with a fever and had to be hospitalized for several weeks. The mission could not wait. General Putnam provided three volunteers, whom Bushnell trained to navigate the vessel. It was twenty-seven-year-old Sergeant Ezra Lee who proved to be the most capable replacement.

Just after midnight on the night of September 6, 1776, Lee slipped into the Turtle and, after two hours of tediously maneuvering the boat with hand cranks, guided it under the sixty-four-gun HMS Eagle, the British flagship. Lee was supposed to attach an explosive charge to the flagship by screwing it to the hull. Some historians speculate that Lee might have hit an iron bar connecting a part of the rudder to the stern, because each time he attempted to twist the bit into the metal of the ship, it would not engage. The hull of the Eagle was sheathed in copper, but Bushnell had anticipated this and had made the auger strong enough to penetrate the weaker metal. While Lee tried to maneuver the submarine to another spot on the hull, the Turtle rose to the surface in broad daylight.

At the mercy of the tide and without the aid of a compass—which, for some reason, was not working—Lee remained four miles from safety. Although he submerged every few minutes, he finally had to remain on the surface to see his way. Lee’s craft was spotted by English sentries on Governor’s Island, and the sentries quickly launched their own boat in a chase. Lee reported that the sailors came within fifty yards of the Turtle but were frightened of what they saw and turned away. Lee released the keg of powder, which drifted harmlessly into the bay and later exploded. Heading back to New York Harbor, Lee was spotted by his own people and towed to shore by a whaleboat.

Lee made several other attempts to destroy British ships in New York Harbor, but all were unsuccessful. When the British advanced up the Hudson River in October, 1776, Bushnell placed his invention aboard a small sloop. A British warship sank the sloop as it fled up the river in an effort to avoid capture. Although Bushnell reportedly recovered his submarine from the depths, its actual fate remains unknown. After the loss of the Turtle, Governor Trumbull had Bushnell commissioned as an officer in the Sappers and Miners Corps of the Continental army, and Bushnell served during the remainder of the war as a demolition expert. After the American Revolution, the reticent inventor moved to Georgia, where he practiced medicine, taught school, and died in obscurity in 1824.

Impact

Although David Bushnell’s submarine failed to sink any enemy vessels, he was responsible for several notable achievements. He was the first to prove that gunpowder could explode underwater with sufficient force to disable and sink a surface ship. He also developed floating and submerged mines and invented the first practical submarine. In so doing, Bushnell solved several basic engineering and nautical problems: constructing a watertight and pressure-proof hull with vertical and horizontal propulsion mechanisms; achieving vertical stability and steering control; and developing the means of using variable ballast systems. Bushnell’s inventions were rapidly improved upon by other U.S. inventors who continued to develop the submarine for use in subsequent U.S. naval conflicts.