Sunday, July 7, 2019

Episode 104: Submarine Warfare

Continental Army in Disarray

At the end of August, 1776, Washington’s army had escaped from Brooklyn, almost by miracle, back to Manhattan, leaving the British in control of Long Island.  Washington’s devastated army was in chaos.  Morale was low and desertions were going through the roof.  It’s as if the soldiers did not want to be stuck in New York City when the British made their next offensive.  Most expected Howe would to land soldiers north of the city and trap Washington’s army on the southern tip of Manhattan, with a British army to the north and the British Navy controlling the harbor to the south and the rivers to the east and west.

With the cannons of the British Navy, Howe’s army easily could have crossed anywhere along the East River and attacked the patriots.  The British had over 400 ships in and around New York, including several large Men-of-War.  Given the deep water all around Manhattan, they could bring artillery fire or land soldiers and marines anywhere they wanted at any time.  Rather than attack though, Gen. Howe took another pause and once again tried to pursue diplomacy.

Attacking the Fleet

During the pause, Washington had time to shore up his defenses on Manhattan.  But no matter how much time he had, he faced the reality that the British controlled the Hudson River (sometimes called the North River at the time) as well as the East River, and all of New York Harbor.  That made any defense of the city impossible.  The British Navy had already proven that the Continental forts defending the rivers were useless.  The Continentals had tried to sink ships in the rivers and create other obstructions that would block Admiral Howe’s ships, but nothing stopped them.

Washington, of course, had no navy to come to his aid.  Most of the small Continental navy remained locked up in Rhode Island.  The few ships that were roaming the Atlantic, along with many privateers could harass isolated British ships, or perhaps even very small convoys, but nothing that dared take on the armada at New York.  So if they wanted to do anything, they needed to get creative.

David Bushnell

The patriots were nothing if not creative.  David Bushnell headed a small team of inventive men looking for a way to attack the British navy.

Bushnell's Turtle (from Wikimedia)
Bushnell is a pretty interesting character.  He was the son of a Connecticut farmer.  He wanted to attend college but could not afford it.  For years, he worked the family farm for subsistence.  While growing up, he attended school, borrowed books when possible, and expressed an interest in mechanics and engineering.  Even so, there seemed to be little chance that he would ever escape farm life.

When his father died in 1762, the 22 year old David and his younger brother Ezra had to take over the family farm.  It was hard work with little reward.  When his younger sister died in 1769, David’s mother remarried.  No longer feeling obligated to support his family, David sold his half of the farm to Ezra and finally pursued his dream of college.  Even though he now had the tuition money, he was not ready to pass the entrance exam.  Undeterred, David moved in with a tutor and spent the next two years working in a local shipyard and studying science and Latin with his tutor.  Finally, at the ripe old age of 31, he started school.  At a time when many students started college at 15 or 16, his classmates called him the old man.

As a member of the graduating class of 1775, Bushnell attended Yale in the years leading up to war.  Expecting a fight, he devoted his studies to developing ways of exploding gunpowder underwater.  While underwater explosives are taken for granted today, the ability to ignite a device underwater that had to stay dry and needed oxygen in the air to explode properly was quite a challenge at the time.  Working with his math professor, Bushnell developed  and tested a gunpowder mine that could ignite from a flintlock attached to a clock mechanism, in other words a time bomb.  He designed small waterproof test devices that he successfully ignited under water.

David Bushnell
(from FindaGrave)
Still getting the explosives to the the ships where they could do damage seemed an impossibility. Guards aboard ship would spot any vessel approaching a warship.  They could raise an alarm and fire on any ship before it could get close enough to explode any device.  No surface ship could approach a naval vessel, even at night.

Bushnell also found an intriguing idea for a delivery device.  Yale’s library had a book Inventions or Devices, published in 1578 by William Bourne of the Royal Navy.  Bourne conceived of and described a wooden enclosure with leather tanks that could take in or force out water to raise or lower the device in the water.  Bourne never build such a device, but it gave Bushnell an idea for building one of his own.  Bushnell also drew inspiration from several others books and articles in the school library.

Bushnell was weeks away from graduation when word of Lexington and Concord reached Yale’s campus in April 1775. The school closed down for a few weeks, but eventually reopened, allowing students to take their final exams and graduate in July.  Many of his classmates headed for Boston to join the new Continental Army.  Bushnell headed back to his family farm in Old Saybrook Connecticut to continue his work on a top secret underwater device.

Building the Turtle

Bushnell kept his project a secret from almost everyone.  With his meager resources, he purchased a small island on the Connecticut River and built a small shack.  There, he told everyone, he was going to become a fisherman.  He would need some help to build his invention.  His brother brother Ezra had already enlisted and was serving at the siege of Boston.  Fortunately, Ezra’s commanding officer was one of David’s Yale classmates, Nathan Hale, who was still a year away from giving his one life for his country.  Bushnell discussed his project with Hale, who allowed Ezra to return home and assist his brother.  Bushnell also recruited a local artisan named Isaac Doolittle to work on a clock mechanism to trigger the explosive.

They made the vehicle by carving out two solid pieces of oak, leaving only one seam to waterproof.  They fastened iron hoops around the wood, like a barrel, to keep it together. The vehicle was only about seven or eight feet long about six feet high and three feet wide, barely enough room to seat the pilot.  Since it was shaped like a turtle shell, they named it the Turtle.

To travel underwater, they developed what they called a "windmill propeller" but is actually a forerunner of the modern screw propeller that others claimed to have invented half a century later. They used a hand crank and foot treadles, similar to what was used with other machinery of the time, to turn the propellers.

Sketch of Turtle (from NavSource)
Snorkels supplied air for the pilot, meaning that the vessel would have to travel near the surface for most of the trip, then rely on the air inside the small operator area when descending near the target. On the top, they attached a hatch made of wood and brass, with windows on all four sides as well as on top so that the pilot could see where he was going.  The windows also provided light when on or near the surface.

The pilot had no light while underwater.  They had tried using a candle, but that quickly burned through the small amount of air in the cabin while submerged.  Instead they added foxfire, a wood fungus that gave off a glow.  They added this to the tip of the compass and the barometer so that the pilot could see direction and depth while underwater and in the dark.

The pilot controlled descent underwater by allowing water into the bottom of the vessel, around the pilot's feet.  Several hundred pounds of lead ballast kept the vehicle from being too light, while adding or removing a little water was enough to help it descend or rise, combined with a vertical propeller that the pilot could also use.

A small team built an underwater mine, containing about 150 pounds of black powder.  A screw would allow it to be attached to the bottom of a ship.  The Turtle would tow the mine on a chain floating alongside the submarine.  Doolittle, who was a clock maker and metal worker by trade, developed a timing device that would allow the pilot to trigger the device then have a few minutes to escape before a flintlock from a gun fired a spark into the gunpowder to trigger the explosion.

During the last summer and fall of 1775, The team tested the Turtle, for weeks on the Connecticut River.  David had tried to pilot the Turtle himself, but found he did not have the necessary strength and stamina.  Instead, brother Ezra took over as pilot.  The men successfully tested their invention by attaching a mine to a wrecked ship and successfully exploded it.

The plan was to propel the Turtle along the surface at night until it got close to a ship.  Then, it would descend underwater, where the pilot would attach the explosive to the bottom of the ship with a screw, set the timing device, and move away before the explosion. The pilot had to perform the entire underwater portion of the operation in 15 to 20 minutes. Otherwise he would run out of air.

The team originally planned to move up to Boston to use against the fleet there.  However, they found they could not use the Turtle in winter.  The Ice made it too hard to navigate.  Also, the foxfire which provided needed light, did not glow in cold weather.

Keeping the Project Secret

Bushnell had attempted to maintain as much secrecy as possible around his project.  Still, he eventually needed to tell some people.  He hoped to get some funding from the Connecticut government and made a proposal to the Governor.  The amount offered was so small that Bushnell decided not to take it.  The presentation, however, meant that Governor Trumbull knew about the project and discussed it with others.

Bushnell also confided in a close friend, Benjamin Gale, who was an inventor and who Bushnell hoped could help with some of their technical problems.  Gale, with Bushnell’s permission, reached out to the most prominent scientist on the continent, Benjamin Franklin.

Turtle in Harbor
One a trip from Philadelphia to Boston, Franklin made a stop in Old Saybrook to get a look at this new contraption.  There are no specific records of what he saw, but Franklin apparently did discuss the project with Washington when he arrived in Boston.

The obvious reason for secrecy was that Bushnell did not want the British to find out about his project and send out a team to destroy it.  Loyalist spies did get word of the project and alerted both General Gage and Royal Governor William Tryon of New York.  Fortunately for Bushnell, both took note of the intelligence, but did not think it important enough to do anything about it.

Bushnell hoped to launch an attack on the fleet in Boston Harbor in the spring of 1776.  The original idea was that the British in Boston only received supplies by sea, and primarily defended their positions with naval cannons.  If the colonists could threaten the navy in Boston Harbor, the army would have to abandon the city. Before he could deploy the Turtle there, the fleet evacuated to Halifax in March after the Continentals occupied Dorchester Heights, something I discussed back in Episode 86.

Bushnell had to wait for a new opportunity to test his craft in combat.  When the British fleet anchored in New York Harbor in June, the team selected Admiral Howe's flagship, the HMS Eagle as the target.

The Attack

Both Governor Trumbull of Connecticut and George Washington approved the attempt.  The team loaded the Turtle aboard a ship on the Connecticut River where they had been testing, and took it to a point near New York Harbor.

Execution of the plan, however, ran into numerous problems.  First the pilot Ezra Bushnell got sick. Historians widely believe that Ezra came down with Typhus, one of the epidemics sweeping through the Continental camp at the time. This man would be out of commission for weeks, if he survived it at all.

The team had to recruit a new pilot for the secret mission. They did not tell the volunteer what the mission was until after he joined the team, out of the need for secrecy.  General Samuel Parsons, also from Connecticut, recommended his brother-in-law, sergeant Ezra Lee to pilot the Turtle for its first mission.

The team put Lee through several weeks of training before he was ready. Finally, once he was familiar with all the controls, the team brought the Turtle overland to New York Harbor. On the night of September 6, about a week after Washington had retreated from Long Island back to Manhattan, the team launched its attack.

Right away, the mission ran into problems.  The Turtle, which took a huge effort to propel forward had to fight an outgoing tide.  Lee describes his attempt to reach the enemy ship: “We set off from the City, the Whale boats towed me as nigh the ships as they dare go, and then they cast me off. I soon found that I was too early in the tide, as it carried me down to the [transport] ships. I however, hove about, and rowed for 5 glasses [2½ hours], by the ship’s bells, before the tide slackened so that I could get along side the man of war, which lay above the transports.

Turtle under the HMS Eagle (from NavSource)
By the time lee had worked himself close enough to his target, it was close to dawn and Lee was exhausted.  Still he descended underneath the ship and attempted to attach the explosive.  “When I rowed under the stern of the ship, could see men and deck and hear them talk-then I shut all doors, sunk down, and came up under the bottom of the ship, up with the screw against the bottom but found that it would not enter.

There is some debate about why Lee could not attach the explosive to the bottom of the ship.  Some have claimed the Eagle had a copper cover underneath the ship to prevent barnacles from attaching and slowing down the vessel.  Others have argued that no, the Eagle did not get a copper bottom until years later and that even if it did, the drill should have been able to bore through it.  Another theory is that Lee was simply unlucky enough to hit on an iron plate near the rudder, which the drill could not penetrate. Whatever the problem was, Lee could not attach the bomb.

Since it had taken him so long to reach the ship and he did not have time to pull away, ascend to get more air, and go back for another try.  With dawn quickly approaching, Lee had to make his escape before being discovered.  As he pulled away from the Eagle, British sentries saw the vessel and sent several guard boats after him to discover what this was.  The Turtle could not outrun a rowboat, so Lee was in real trouble.

Lee detached his explosive and set the timing device, hoping to take out his pursuers, and possibly himself as well.  As he put it, he “let loose the magazine in hopes, that if they should take me, they should likewise pick up the magazine, and then we should all be blown up together…”  The explosive drifted away from the Turtle, and a few minutes later, exploded harmlessly away from everyone, sending a column of water into the air.  That was enough for the British sailors to call off their pursuit.  After seeing one wooden device explode, they did not want to get near the other wooden device that they saw, for fear it was another explosive as well.

The British turned back.  Lee was able to propel the Turtle back to the American lines near the shore.

End of the Experiment

The Americans recovered the Turtle and prepared for a second attempt further up the Hudson river.  The British, now alerted to the danger, discovered the vessel on two subsequent attempts to make contact with the enemy and fired on it.  In both cases, the pilot was able to make his escape, but without being able to attach the explosive.  Shortly after this, the British navy sank the transport vessel carrying the Turtle.  With the loss of the vessel after three unsuccessful attempts, the American submarine project came to an end.

Mine used to destroy a British
ship near Philadelphia
(from Wikipedia)
So, the project was a failure.  The Turtle did not damage any British ships and forced no British reaction other than keeping nighttime sentries aboard ship a little more alert.  Admiral Howe did not see the technology as a threat and did not change his ship deployments.  Still, it is pretty amazing that that Patriots built and deployed a submarine at all.  During the war, the project remained secret.  It did not become well known until long after the war ended.

Bushnell later wrote that he had recovered the Turtle from the shipwreck.  If he did, the Americans never used it again.  Some speculate that he recovered and hid the parts for future use.  If he did, the chance never came because the Americans never tried this experiment again for the rest of the war.

Although this was the end of the Turtle, Bushnell continued his efforts to sink British ships with his underwater explosives.  The following year, the Americans deployed underwater mines with spring loaded triggers.  Any ship that hit the mine could trigger an explosion.  By this time, the British had occupied Philadelphia, so the Americans deployed about twenty mines in the Delaware River, just upstream from the city.  They successfully blew up a barge, killing four sailors. It was enough to alert the entire city to a possible attack.  Sentries fired at the mines, destroying several, while the remainder floated past the city.   Sadly, one of the mines which floated past Philadelphia caught the attention of a couple of boys fishing. It exploded and killed them as they attempted to haul the strange device into their boat.

Bushnell took a captain’s commission in the Continental army and served in the newly formed Corps of Sappers and Miners, what eventually became the Army Corps of Engineers.  After the war, he returned to Connecticut, but after the death of his brother Ezra in 1787, he left for good.  Some say  he want to France.  There is some evidence that Bushnell tried to make contact with French Ambassador Thomas Jefferson, in hopes of selling his submarine to the French Navy.

A few years later, a man named David Bush moved to Georgia, working as a teacher and physician.  When he died years later, he left his small estate to Ezra’s children, thus revealing his true identity.  It’s not clear why Bushnell changed his name and moved to Georgia, but he died without his friends and neighbors knowing about his exploits during the war.  The submarine would have to wait almost another century before the Confederates would try to use it again during the Civil War.

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Next  Episode 105: Staten Island Peace Conference

Previous  Episode 103: The Battle of Brooklyn

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Further Reading


David Bushnell and his Revolutionary Submarine, by Brenda Milkofsky:

David Bushnell Facts:

David Bushnell:

David Bushnell and the American Turtle:

Speck, Robert M. "The Connecticut Water Machine Versus The Royal Navy" American Heritage Magazine Vol. 32 Issue 1, Dec. 1980:

Free eBooks
(from unless noted)

David Bushnell and his American Turtle, New York: The Werner Company, 1899

Fyfe, Herbert C. Submarine Warfare, Past, Present and Future, London: Grant Richards, 1902.

Wagner, Frederick Submarine Fighter of the American Revolution: the Story of David Bushnell, Dodd Mead & Co. 1963 (available as loan).

Books Worth Buying
(links to unless otherwise noted)*

Daughan, George C. Revolution on the Hudson: New York City and the Hudson River Valley in the American War of Independence, New York: W.W. Norton & Co. 2016.

Ellis, Joseph Revolutionary Summer: The Birth of American Independence, New York: Alfred A. Knopf, 2013.

Fleming, Thomas 1776: Year of Illusions, New York: W.W. Norton & Co., 1975.

Gallagher, John J. Battle Of Brooklyn, 1776,  Da Capo Press, 1995.

Lefkowitz, Arthur S. Bushnell’s Submarine, New York: Scholastic, 2006.

Manstan, Roy & Frese, Frederic Turtle: David Bushnell's Revolutionary Vessel, Yardley, Pa: Westholme Publishing, 2010 (book recommendation of the week).

Schecter, Barnet The Battle for New York, New York: Walker Publishing, 2002.

Wagner, Frederick Submarine Fighter of the American Revolution: the Story of David Bushnell, Dodd Mead & Co. 1963 (co-book recommendation of the week).

* As an Amazon Associate I earn from qualifying purchases.

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