Saturday, January 2, 2016

Submarine Warfare in the American Revolution

Listen to a podcast of this episode.

Most people think about submarine warfare beginning with the WWI German U-boats.  But military inventors have been looking for ways to use the cloak of underwater travel for centuries.

The American Revolution saw submarine warfare, although it is not widely remembered as it was not a success.  Still, I think it is an amazing example of the daring and ingenuity of the men who fought that war.
Artist's rendering of
Bushnell's Turtle

In the summer of 1776, the British fleet arrived in New York Harbor.  The Americans had no real navy at the time, certainly nothing that could challenge the British.  They were looking for an effective way to attack.

David Bushnell was a recent graduate of Yale College.  While at school, Bushnell worked at developing ways of exploding gunpowder underwater.  While underwater explosives are taken for granted today, the ability to ignite a device under water that had to stay dry and needed oxygen in the air to explode properly was quite a challenge at the time.  Bushnell was able to develop some effective underwater explosives during his time at school, a project that would likely be widely frowned upon at most colleges today.

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.

Building the Turtle

David Bushnell and his brother Ezra, as well as a local artisan named Isaac Doolittle began work on a delivery device that could travel under water.  They made the vehicle out of oak, held together with iron hoops like a barrel. 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.

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. Similarly a small window in the top hatch provided light when on or near the surface, but no light was available during the descent.  The pilot controlled descent underwater by allowing water into the bottom of the vessel, around the pilot's feet.

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.  Doolittle, who was a clock maker 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.

The team tested the vehicle, named the Turtle for weeks on the Connecticut River.  Ezra Bushnell, David's brother, served as the pilot.  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. With the British fleet in New York Harbor, the team selected Admiral Howe's flag ship, the HMS Eagle as the target.

The Attack:

Execution of the plan, however, ran into numerous problems.  First the pilot Ezra Bushnell became feverishly ill and was not fit for duty.  A new pilot, Ezra Lee had to be trained, taking several more weeks.  Eventually the team brought the Turtle to New York Harbor.  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.”

By this time, 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.”  Sadly for the American effort, the Eagle had a copper cover underneath the ship to prevent barnacles from attaching and slowing down the vessel.  The Turtle's screw was designed to bore through wood, but could not pierce the metal.

Now daylight, Lee decided to make his escape before being discovered.  The British saw the vessel and sent several guard boats after him to discover what this was.  Lee detached his explosive and set the timing device, hoping to take out his pursuers, and possibly himself as well.  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 explosion was not near enough to any vessels to cause any damage, but the distraction was enough to allow Lee to make his escape and reach the shore.

Later Efforts:

The patriots 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 upon 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 nave sank the transport vessel carrying the Turtle.  With the loss of the vessel after three unsuccessful attempts, the Patriot submarine project came to an end.

David Bushnell went on to develop several under water mines that were used against British ships. In 1777 he attempted to use a floating mine to blow up the HMS Cerberus near New London Connecticut. The mine struck a smaller boat near the Cerberus.  The explosion killed four enemy four sailors and destroyed the boat.  The Cerberus, however, escaped.  In 1778 Bushnell floated several mines down the Delaware River to attack anchored British ships.  The mines missed their targets, but killed two young civilians.

Bushnell's Career

David Bushnell
Despite a lack of any real success, the Continental Army continued to see potential in Bushnell's efforts.  In 1778, General Washington proposed the formation of a new military unit to be known as the "Corps of Sappers and Miners".  Bushnell was given command of the Corps in 1779.  Near the end of the War in 1783, he became Commander of the Army Corps of Engineers as West Point.  There, he continued his work developing new technology for the Army.

After the war Bushnell left the military.  He spent several years in France.  Eventually he returned to the US, setting in Georgia where he worked as a college professor and medical Doctor.  For unknown reasons, he had changed his name to David Bush.  He never married or had any children.  He also continued to work on underwater explosives and delivery devices later in life as well.  He was still seeking a new contract with the US Army shortly before his death in 1824.  A model torpedo was found among his possessions after he died.


The project remained a military secret throughout the war.  It did not become generally known until Thomas Jefferson gave a lecture on the subject to the American Philosophical Society in Philadelphia in 1798.  Bushnell had corresponded with Jefferson about the military venture after the war had ended.  Submarine warfare, however, was shelved.  The US Navy would not commission its first submarine until more than a century later.

Honored as the father of Submarine Warfare, the US Navy has named two ships USS Bushnell, one in operation during WWI and a second in WWII.

Listen to a podcast of this episode.

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