CSS Hunley Civil War Submarine model. Privately invented by Horace Lawson Hunley and built in 1863 by Park and Lyons of Mobile, Alabama, Hunley was fashioned from a cylindrical iron steam boiler, which was deepened and also lengthened through the addition of tapered ends. Hunley was designed to be hand powered by a crew of nine: eight to turn the hand-cranked propeller and one to steer and direct the boat. As a true submarine, each end was equipped with ballast tanks that could be flooded by valves or pumped dry by hand pumps. Extra ballast was added through the use of iron weights bolted to the underside of the hull. In the event the submarine needed additional buoyancy to rise in an emergency, the iron weight could be removed by unscrewing the heads of the bolts from inside the vessel.
The Confederate Navy seized the boat from its private builders and owners a few weeks after its arrival in Charleston, South Carolina.
Three of the Hunley's night missions failed against the Union ironclads blockading the harbor. Then on August 29, 1863 five of a crew of nine were killed during an attempted attack when the skipper accidentally dived with the hatches open. October 15, 1863 the Hunley sank during another attempt, killing its inventor Horace Lawson Hunley and seven other crewmen.
On February 17, 1864, the Confederate submarine made a night attack on the USS Housatonic, a 1800-ton sloop-of-war with 23 guns, in Charleston Harbor off the coast of South Carolina. H.L. Hunley rammed Housatonic with a torpedo packed with explosive powder attached to a long spar on its bow. The torpedo embedded in the sloop's wooden side was detonated by a rope as Hunley backed away. The resulting explosion that sent Housatonic with five crew members to the bottom of Charleston Harbor probably also sank Hunley with its crew of nine although this is not certain. H.L. Hunley earned a place in the history of undersea warfare as the first submarine to sink a ship in wartime.