The Trial of a Spar Torpedo - American History, 1493-1945

Back to Science, Technology and Industry

Richard T. Renshaw to Henry K. Davenport reporting on the successful trial of a spar torpedo

8 November 1862

View the letter from Richard T. Renshaw to Henry K. Davenport in the resource

Written in November 1862, this short letter from Richard T. Renshaw to senior Union officer, Henry K. Davenport, details the successful testing of an early device for "blowing up vessels" that would go on to change the practice of naval warfare around the globe.

The invention that Renshaw wrote about was John L. Lay’s spar torpedo. He describes the weapon as "[a] cylinder containing ninety pounds of powder […] moored in ten feet water" and explains how a sixty ton schooner floated over the channel that concealed the torpedo and caught in its wires, subsequently "blowing her to atoms". Renshaw goes on to write that three more torpedoes are currently under construction, and assures Davenport that he will send drawings as soon as possible.

Primitive in comparison to modern torpedoes, these non-propellant weapons functioned like mines, detonating on contact or after a set time, and led to a series of decisive maritime victories during the Civil War. Two years later during a daring mission in North Carolina, Lieutenant William B. Cushing used a spar torpedo to sink the Confederate ironclad, CSS Albemarle. Southern forces also had access to crude torpedoes. At the outbreak of the conflict, Virginian oceanographer, Matthew Fontaine Maury, resigned his commission in the U.S. Navy and dedicated himself to the defence of southern waterways, proposing electric mines (or torpedoes) that could be floated across rivers. Though both sides had access to the explosives, the Confederacy arguably employed them with greater success, destroying dozens of enemy ships while the Union navy sank only six. Ingenious though they were, torpedoes were not always effective. Immortally, during his charge into Mobile Bay in 1864, Union admiral, David Farragut, was said to shout, "Damn the torpedoes!" as he ploughed through a minefield without harm. Nevertheless, the rivers and seaboard of the southern states proved a fruitful testing ground for a weapon that would prove integral to battles at sea throughout the following century.

Ironclad warships would clash for the first time in the naval theatre of the Civil War, while undersea warfare would also take considerable leaps forward during this period. Although not completely submersible, Confederate submarine, the H. L. Hunley, managed to destroy a Union ship using a pole-mounted torpedo. In doing so, it became the first submarine to successfully sink an enemy ship. From torpedoes, to ironclads to combat submarines, the technological advancements made by both northern and southern forces during the conflict heralded the dawn of America’s military dominance on the world stage. Though rudimentary, the varying successes of these war-time inventions would foster a lasting culture of scientific experimentation, securing the nation’s place at the forefront of martial innovation throughout the following century and beyond.

The Successful Trial of a Spar Torpedo