The ability to strike silently and invisibly from below the waves has enticed naval planners for centuries. In the late 15th century, OG renaissance man Leonardo da Vinci sketched out various designs for military diving suits and submersibles, and even claimed to have devised a method for remaining underwater for extended periods. However, he never described these methods in detail, writing in his notebook:
“I do not describe my method of remaining under water and how long I can remain without eating. And I do not publish nor divulge these, by reason of the evil nature of men, who would use them for assassinations at the bottom of the sea by destroying ships, and sinking them, together with the men in them.”
Sure, Leonardo…
It would be another 100 years before the world’s first navigable submarine was built by Dutch engineer Cornelis Jacobzoon Drebbel, court inventor to King James I of England. Constructed in the manner of two wooden rowboats joined together and covered in leather to make it watertight, Drebbel’s craft was propelled by oars fitted through flexible leather gaskets and featured a rudder for steering and pigskin bladders connected to the exterior of the hull which acted as ballast tanks. Ordinarily, the necks of the bladders were tied off using string; to dive the vessel, the strings were untied, allowing water to rush in. To surface, the crew squeezed the bladders, forcing the water out and increasing the vessel’s buoyancy. Even more impressive, Drebbel’s design reportedly included a system for maintaining a breathable atmosphere. Though the details were not recorded, it is likely that Drebbel heated potassium nitrate or saltpeter to generate oxygen and laid out trays of sodium hydroxide or lye to absorb carbon dioxide. Between 1620 and 1624 Drebbel constructed three submarines of increasing size, with the third and final model being propelled by six oars and capable of carrying up to 16 passengers. This craft was tested in the River Thames many times, with contemporary reports claiming that it could travel from Westminster to Greenwich and back in around three hours while submerged at a depth of 3-4 metres. King James himself is even said to have taken a short ride, making him the first monarch to travel underwater. However, several historians argue that these claims are highly exaggerated, and that Drebbel’s craft was little more than a semi-submersible capable only of drifting with the current. Whatever the case, despite 15 years of development and demonstrations, Drebbel failed to interest the Royal Navy in his design, and the project was ultimately abandoned.
Though many inventors over the following decades would try their hand at creating military submarines, it would not be until the late 18th century that technology that technology had advanced sufficiently to make this dream a practical reality. Enter David Bushnell and the Turtle.
David Bushnell was born on August 30, 1740 in Westbrook, Connecticut, the son of farmers Nehemiah and Sarah Bushnell. The early part of his life is poorly documented and appears to have been largely uneventful, with Bushnell spending much of his spare time on the family farm reading up on various scientific and technical topics. It was not until 1766, following the death of his parents and two sisters, that he decided to spend his inheritance and pursue a formal education. In 1771 at the age of 31, he was accepted into Yale College.
At Yale, Bushnell and colleague Phineas Pratt researched the problem of detonating gunpowder charges underwater, which was previously thought impossible. However, starting with two ounces of gunpowder and gradually working his way up, Bushnell eventually developed a waterproof explosive charge capable of sinking a military vessel, which contained two pounds of gunpowder and was set off by a clockwork timer connected to the flintlock sparking mechanism from a musket. Though known today as naval mines, at the time such devices were referred to as torpedoes after the torpedo fish or electric ray, which delivers a powerful electric shock to stun its prey. Thus, when Rear Admiral David Farragut issued his immortal command “Damn the torpedoes! Full speed ahead!” at the 1864 Battle of Mobile Bay, he was referring to stationary mines and not modern motor torpedoes, which would not be perfected for another half-century.
After graduating from Yale, Bushnell returned to his brother Ezra’s farm near Old Saybrook, Connecticut, where he began building a small, one-man submersible to stealthily deploy his ingenious torpedoes against enemy warships. At the time, tensions between the British authorities and the American colonies were steadily rising. They would eventually boil over on April 19, 1775 with the firing of the “shot heard round the world” at Lexington and Concord, which touched off the American Revolutionary War.
Built in cooperation with his brother Ezra, Phineas Pratt, and brass worker and clockmaker Isaac Doolittle, Bushnell’s pear-shaped craft measured 2.3 metres long by 1.8 metres deep by 1.8 metres wide and was built from oak staves bound together with iron hoops like a barrel. As the two halves of the hull resembled turtle shells, the vehicle was dubbed the Turtle. The hull was topped by a small brass conning tower with glass viewports which could be hinged open for ingress and egress, and was propelled through the water by a pair of brass propellers – one on the front for horizontal motion and one on top for vertical motion. Incredibly, this was the first recorded use of screw propellers on a vessel of any kind – predating the widespread adoption of this technology on steamships by nearly one hundred years. These, like all the Turtle’s brass fittings were designed and cast by Isaac Doolittle.
Inside the hull, the operator drove the forward propeller using a set of foot pedals and steered the Turtle with a rudder connected to a wooden tiller. The craft was kept upright by lead ballast, and submerged and surfaced by pumping water in and out of ballast tanks under the operator’s feet. For navigation, the operator was provided with a depth gauge and a compass, the needles of which were fitted with pieces of bioluminescent foxfire fungus so that they could be read in the dark. The hull held enough air for around 30 minutes of submerged operation, whereupon the operator was forced to surface and replenish the air using a bellows and a set of ventilator pipes attached to the conning tower. The Turtle was armed with a single 150 lb gunpowder charge with a clockwork delay fuze, which could be screwed into the hull of a target ship using a hand-cranked auger.
Due to the builders’ commitment to secrecy, records of the Turtle’s development and testing are spotty. It is known that in 1771 Bushnell met with Jonathan Trumbull, the governor of Connecticut, seeking funds to help complete the submarine. Trumbull duly forwarded Bushnell’s request to Thomas Jefferson and General George Washington. And on November 9, 1775, one of Bushnell’s Yale classmates, Dr. Benjamin Gale, wrote to Silas Deane, a delegate to the Continental Congress:
“I now write with the greater freedom, as I conclude by the time this reaches you the machine will be in camp. Lately he has conducted matters and his designs with the greatest secrecy, both for the personal safety of the navigator as to produce the greatest astonishment to those against whom it is designed, if this projection succeeds, of which I make no doubt, as I well know the man and have seen the machine while in embryo, and every addition made to it fills me with fresh astonishment and surprize. And you may call me a visionary, an enthusiast, or what you please, – I do insist upon it, that I believe the inspiration of the Almighty has given him understanding for this very purpose and design. If he succeeds, a stipend for life, and if he fails, a reasonable compensation for time and expense is his due from the public.
What astonishment it will produce and what advantages may be made by those on the spot, if it succeeds, is more easy for you to conceive than for me to describe.
I congratulate you and my country in the begun success of our Arms to the northward, and the prospects of further success. Make my most respectful compliments to Dr. Franklin and our Delegates, your associates; and am, most respectfully your sincere friend and most humble servant.”
Soon after, Benjamin Franklin visited Bushnell in Old Saybrook and toured the still-incomplete Turtle. While Franklin and Jefferson, avid inventors in their own right, were intrigued by the project, Washington was initially hesitant to commit any more of the Continental Army’s already stretched budget. However, he eventually relented and some funds were released.
Nonetheless, construction and testing of the Turtle proceeded slowly, the project being beset by numerous technical difficulties. For example, the operation of the submarine required considerable stamina and coordination on the part of the operator, who not only had to crank the propellers and operate the rudder, but also navigate, continuously adjust the craft’s depth, and also perform the complex task of fixing its explosive payload to the target. Indeed, during initial testing at Ayer’s Point on the Connecticut River, David Bushnell discovered he was far too frail to pilot the craft, and instead designated the task to his brother Ezra of the Continental Army. Another unexpected difficulty was that in cold weather, the foxfire fungus fixed to the instrument dials lost its luminescence, making the instruments impossible to read. On December 7, 1775, Dr. Benjamin Gale wrote to his colleague Silas Deane asking:
“…[if you could] enquire of Dr. Franklin whether he knows of any kind of phosphorus which will give light in the dark and not consume the air. He has tried a candle, but that destroys the air so fast he cannot remain under water long enough to effect the thing.”
However, no solution was forthcoming, forcing Bushnell and his colleagues to sideline the Turtle over the winter months. These delays elicited considerable skepticism and annoyance throughout the Continental Army, with militia leader Samuel Osgood writing to John Adams in October 1775 that:
“The famous Waters Machine from Connecticutt is every Day expected in Camp. It must unavoidably be a clumsy Business as its Weight is about a Tun. I wish it might succeed [and] the Ships be blown up beyond the Attraction of the Earth for it is the only Way or Chance they have of reaching St. Peters Gate.”
Indeed, while the Turtle was originally intended to counter the blockade of Boston Harbour, by March 1776 the British fleet had already withdrawn to Halifax in Nova Scotia. However, the Royal Navy still occupied New York Harbour, which soon became the Turtle’s new target. In the late summer of 1776, General Washington met with David Bushnell to finalize the plan of attack, and the completed Turtle was transported from Old Saybrook to Long Island Sound. On August 27, the Battle of Long Island ended with the British taking control of the western half of the island, forcing the Turtle to be moved again to New Rochelle on the Hudson River. At the same time, Ezra Bushnell suddenly fell ill, and David asked General Samuel Parsons to find volunteers. Sergeant Ezra Lee of the Continental Army soon stepped forward, and spent two weeks familiarizing himself with the submarine’s operation. Finally, in early September, 1776, Turtle was towed to lower Manhattan and made ready for its first mission.
At 11 PM on September 7, 1776, Sergeant Lee climbed aboard the Turtle and set off down the Hudson River into New York Harbour. His target was HMS Eagle, a sixty-four-gun ship of the line and flagship of Admiral Richard Howe, moored off Governor’s Island. It was hoped that destroying such a valuable and symbolic target would deal a serious blow to British morale. The journey to the anchorage was a gruelling one, with Lee having to fight a stiff tidal current and navigate the harbour in near-complete darkness. His thirty-minute air supply also forced him to surface frequently along the way. But at last, two hours after casting off, he reached the Eagle undetected and set about deploying his deadly cargo.
But once again, Lee ran into serious problems. Still fighting the current, overwhelmed by having to simultaneously operate the propellers, rudder, ballast pump, and torpedo auger, and likely suffering from carbon dioxide poisoning, Lee struggled to keep the Turtle in position beneath the Eagle. Worse still, when he tried to drill into the Eagle’s hull, the auger refused to penetrate. It is often claimed that Lee was defeated by copper plates on the hull designed to counter wood-eating shipworms; however, the Eagle had not yet been fitted with such plates, and in any case the plates themselves were paper thin and would have offered no resistance to Lee’s auger. More likely, the wood was simply harder than anticipated or Lee had accidentally struck an iron plate connected to the ship’s steering mechanism. Whatever the case, with daylight approaching an exhausted Lee soon abandoned the attempt and surfaced the Turtle to replenish his air supply. He was soon spotted by British soldiers stationed on Governor’s Island, who rowed out in a small boat to investigate. Thinking quickly, Lee armed and released his torpedo and started heading back to base. Upon spotting the small floating shape, the soldiers grew suspicious and withdrew, allowing Lee to slip away. The torpedo drifted into the East River, where it eventually detonated, throwing up a huge column of spray.
Though unsuccessful, the September 7, 1776 attack on HMS Eagle marked the first time in recorded history a submersible craft had been used in combat. Over the next few months two more, less well-documented attacks were carried out against British shipping, though these, too, were unsuccessful. And before the Turtle could be deployed again, the sloop serving as its tender was sunk by British forces on November 20, 1776 during the Battle of Fort Lee. Bushnell claimed to have successfully salvaged the submarine, though due to budget constraints it was never used in combat again. To this day, the ultimate fate of the historic craft remains a mystery.
Undaunted, Bushnell continued to develop various schemes involving underwater explosives. On August 13, 177, he launched an attack against the British frigate HMS Cerberus in Black Point Bay, Connecticut – a mission later recorded by physician and writer James Thacher in his Military Journal During the American Revolutionary War:
“In the year 1777, Mr. Bushnell made an attempt from a whale-boat, against the Cerberus frigate lying at anchor, by drawing a machine against her side, by means of a line. The machine was loaded with powder, to be exploded by a gun-lock, which was to be unpinioned by an apparatus to be turned by being brought alongside of the frigate. This machine fell in with a schooner at anchor astern of the frigate, and concealed from his sight. By some means it became fixed, and exploding, demolished the schooner.
Commodore Simmons…discovered about eleven o’clock in the evening a line towing astern from the bows. He believed that some person had veered away by it, and immediately began to haul in. A sailor, belonging to the schooner, taking it for a fishing line, laid hold of it, and drew in about fifteen fathoms. It was buoyed up by small pieces of wood tied to it at stated distances. At the end of the rope a machine was fastened, too heavy for one man to pull up, for it exceeded one hundred pounds in weight. The other people of the schooner coming to his assistance, they drew it on deck. While the men were examining the machine, about five minutes from the time the wheel had been put in motion, it exploded, blew the vessel into pieces, and set her on fire. Three men were killed, and the fourth blown into the water, much injured.
On examining round the ship, after this accident, the other part of the line was discovered, buoyed up in the same manner. This the commodore ordered to be instantly cut away, for fear of hauling up another of the infernals, as he termed it. These machines were constructed with wheels, furnished with irons sharpened at the end, and projecting about an inch, in order to strike the sides of the vessel when hauling them up, thereby setting the wheels in motion, which in the space of five minutes causes the explosion. Had the whole apparatus been brought to operate on a ship at the same time, it must have occasioned prodigious destruction.”
Then, on January 1778, Bushnell launched a salvo of floating mines down the Delaware River, hoping they would contact and destroy British ships anchored in Philadelphia harbour. However, the British had arranged their ships to avoid being struck by floating river ice, and this in turn protected them from the mines. The only casualties of the attack were two young boys who stumbled upon a mine and were killed in the resulting explosion. Nonetheless, the attack caused great consternation among the British forces, which was lampooned in a humorous ballad by composer Francis Hopkinson titled The Battle of the Kegs:
‘Twas early day, as poets say,
Just when the sun was rising,
A soldier stood, on a log of wood,
And saw a thing surprising.
As in amaze he stood to gaze,
The truth can’t be denied, sir,
He spied a score of kegs or more, 1
Come floating down the tide sir.
A sailor, too, in jerkin blue,
This strange appearance viewing,
First damn’d his eyes, in great surprise,
Then said, “some mischief’s brewing.
“These kegs, I’m told , the rebels hold,
Packed up like pickled herring,
And they’re come down, t’ attack the town,
In this new way of ferrying.”
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.
Following this failed attack, both the Connecticut government and the Continental Army refused to fund further work on mines or other underwater explosives. Instead, General Washington commissioned David Bushnell as a captain-lieutenant in the U.S. Army Corps of Engineers, in which he served with distinction. Following the end of the Revolutionary War, Bushnell slipped into obscurity, moving first to France and then to Warrenton, Georgia where he worked as a schoolteacher and studied and practiced medicine until his death in 1824.
Though his inventions had little impact on the course of the war, Bushnell was nonetheless widely admired and respected by his superiors, with George Washington stating in a 1785 letter to Thomas Jefferson:
“Bushnell is a man of great Mechanical powers – fertile of invention – and a master in execution. He came to me in 1776 recommended by Governor Trumbull (now dead) and other respectable characters who were proselites to his plan. Although I wanted faith myself, I furnished him with money, and other aids to carry it into execution. He laboured for sometime 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, to expect much success from the enterprise against an enemy, who are always upon guard. That he had a machine which was so contrived as to carry a man under water at any depth he chose, and for a considerable time and distance, with an apparatus charged with powder which he could fasten to a ships bottom or side and give fire to in any given time (sufficient for him to retire) by means whereof a ship could be blown up, or sunk, are facts which I believe admit of little doubt. But then, where it was to operate against an enemy, it is no easy matter to get a person hardy enough to encounter the variety of dangers to which he must be exposed: 1, from the novelty, 2 from the difficulty of conducting the machine, and governing it under water on account of the currents, and 3 the consequent uncertainty of hitting the object of destination, without rising frequently above water for fresh observation, which, when near the vessel, would expose the adventurer to a discovery, and almost to certain death
To these causes I always ascribed the non-performance of his plan, as he wanted nothing that I could furnish to secure the success of it. This to the best of my recollection is a true state of the case.”
Indeed, while the basic concept of the Turtle was sound, Bushnell was limited by the technology of his day. Human muscle power alone was insufficient to counter the strong currents and other forces encountered under real combat conditions, while the need to manipulate several controls at once quickly grew overwhelming for even the most experienced operator. And without a means of storing or generating extra oxygen and absorbing carbon dioxide, the Turtle’s submerged endurance was highly limited. In future submarines, all these various functions would be divided among multiple crewmen, greatly easing the operation of the vessel.
Interestingly, some historians suggest that the Turtle as described by Bushnell was never actually used in combat, and that the entire story was either propaganda or that the 1776 attack on HMS Eagle was carried out using a covered rowboat and not a true submersible. Whatever the case, today David Bushnell is widely regarded as the father of the combat submarine, with two U.S. Navy submarine tender ships being named in his honour – one in 1915, and another in 1942.
But it would be another century before a submarine finally succeeded in sinking an enemy vessel in combat. On the evening of February 17, 1864, the Confederate submarine CSS H.L. Hunley attacked the Union sloop-of-war USS Housatonic, one of dozens of ships blockading the harbour at Charleston, South Carolina. Powered by a long hand-crank driven by seven men, the Hunley carried a 61 kilogram spar torpedo – a metal canister of gunpowder fitted with a barbed harpoon head and fitted to the end of a 7 metre long pole. The torpedo was designed to be rammed into the side of the target ship, whereupon the submarine would retreat to a safe distance and pull a long cord attached to the firing mechanism, setting off the charge. While the mission was successful, the Hunley and her crew were never heard from again, the wreck not being rediscovered until 1995. Though crude and highly dangerous like her predecessor the Turtle, the Hunley nonetheless provided naval planners with a tantalizing glimpse of what was to come.
Expand for References
Parrish, Thomas, The Submarine: a History, Penguin Group, New York, 2004
David Bushnell, Encyclopedia Britannica, https://www.britannica.com/topic/Turtle-submarine
“Turtle” Submarine, Connecticut River Museum, https://ctrivermuseum.org/turtle-submarine/
Rockwood, Heather, The Turtle: Submarine Warfare During the American Revolution, The Beehive, June 22, 2022, https://www.masshist.org/beehiveblog/2022/06/the-turtle-submarine-warfare-during-the-american-revolution/
Bushnell’s Turtle: a Revolutionary Submarine, American Battlefield Trust, July 25, 2022, https://www.battlefields.org/learn/articles/head-tilting-history/bushnells-turtle-revolutionary-submarine
The Submarine Turtle: Naval Documents of the Revolutionary War, Naval History and Heritage Command, https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/s/submarine-turtle-naval-documents.html
Hanlon, Mike, Cornelius Drebbel Built Three Submarines in the 1620s – They All Worked, New Atlas, February 16, 2005, https://ift.tt/WipfcaO
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