H. L. Hunley was a submarine of the Confederate States of America that played a small part in the American Civil War, but a large role in the history of naval warfare. The Hunley demonstrated both the advantages and the dangers of undersea warfare. It was the first combat submarine to sink an enemy warship, although the Hunley was not completely submerged and was lost at some point following her successful attack. The Confederacy lost 21 crewmen in three sinkings of the Hunley during her short career. The submarine was named for her inventor, Horace Lawson Hunley, shortly after it was taken into service under the control of the Confederate Army at Charleston, South Carolina.
The Hunley, nearly 40 feet (12 m) long, was built at Mobile, Alabama, and launched in July 1863. It was then shipped by rail on August 12, 1863 to Charleston, South Carolina. Hunley (then called Fish Boat) sank on August 29, 1863, during a training exercise, killing five members of her crew. It sank again on October 15, 1863, killing all eight of her second crew, including Horace Hunley himself, who was aboard at the time, even though he was not enlisted in the Confederate armed forces. Both times the Hunley was raised and returned to service. On February 17, 1864, Hunley attacked and sank the 1240-short ton (1124 metric
tons) screw sloop USS Housatonic on Union blockade duty in Charleston's outer harbor. Soon after, Hunley sank for unknown reasons, killing all eight of her third crew. This time, the innovative ship was lost.
Hunley and two earlier submarines were privately developed and paid for by Horace Lawson Hunley, James McClintock, and Baxter Watson.
Hunley, McClintock, and Watson first built a small submarine named Pioneer in New Orleans, Louisiana. Pioneer was tested in February 1862 in the Mississippi River and was later towed to Lake Pontchartrain for additional trials. But the Union advance towards New Orleans caused the men to abandon development and scuttle Pioneer the following month. The poorly documented Bayou St. John Confederate submarine may have been constructed about the same time as Pioneer.
The three inventors moved to Mobile and joined with machinists Thomas Park and Thomas Lyons. They soon began development of a second submarine, American Diver. Their efforts were supported by the Confederate States Army; Lieutenant William Alexander of the 21st Alabama Infantry Regiment was assigned oversight duty for the project. The men experimented with electromagnetic and steam propulsion for the new submarine, before falling back on a simpler hand-cranked propulsion system. American Diver was ready for harbor trials by January 1863, but it proved too slow to be practical. One attempted attack on the Union blockade was made in February 1863 but was unsuccessful. The submarine sank in the mouth of Mobile Bay during a storm later the same month and was not recovered.
Hunley made her first and only attack against a live target on the night of February 17, 1864. The vessel was the USS Housatonic. Housatonic, a 1240-ton (1.1 million-kilogram) steam-powered sloop-of-war with 12 large cannons, was stationed at the entrance to Charleston, South Carolina harbor, about 5 miles (8 kilometers) out to sea. In an effort to break the naval blockade of the city, Lieutenant George E. Dixon and a crew of seven volunteers attacked Housatonic, successfully embedding the barbed spar torpedo into her hull. The torpedo was detonated as the submarine backed away, sending Housatonic and five of her crew to the bottom in five minutes, although many survived by boarding two lifeboats or by climbing the rigging until rescued.