In 1863, hard-pressed by the Federal blockade, the Confederate States Navy began to make use of “special attack” submersibles. The first to see action were semi-submersibles called Davids to emphasize their giant-killing role. The David was a small, cigar-shaped steam-boat with a four-man crew. It was armed with a spar-torpedo – a 20ft (6m) pole projecting from the bow and ending in a copper canister containing 134lb (61kg) of gunpowder, fired by a chemical impact fuze. Intended for night operations, the David could be trimmed down for attack until only her funnel and superstructure were above water. On the night of 5 October 1863, a David commanded by Cdr W. T. Glassell, CSN, survived an attack in which she severely damaged the Federal ironclad New Ironsides off Charleston.
The Confederate States Army now took a hand with a true submersible – the fifth in a series built at Mobile, Alabama, by Horace A. Hunley. This 19 ton (19.3 tonne) craft was an iron tube some 30ft (9m) long and 5ft (1.5m) in beam, propelled by a stern-mounted screw cranked by eight men. It had a squat conning tower at either end as the commander’s station, with hydroplane and rudder controls, and was armed first with a towed explosive charge and then with a 134lb (61 kg) spar-torpedo with a barbed end. The craft normally ran awash but was theoretically capable of submerging for up to two hours. Simply to crew this submersible was suicidal: it was totally unstable and sank four times during trials, killing 33 men – including Hunley himself. The inventor was posthumously honoured by having the first operational model bear his name.
CSS Hunley slipped out of Charleston on the evening of 17 February 1864 to strike at the patrolling USS Housatonic. Lt George E. Dixon, CSA, Hunley’s commander, intended to drive home the barb of his spar-torpedo below the waterline of the 20-gun sloop. He would then back water, unreeling a lanyard that would fire the charge when Hunley was at a safe distance. The ramming attack succeeded and Housatonic swiftly sank, taking down with her five of her crew – and the nine men of Hunley, which was dragged down with her victim. In spite of the obviously suicidal nature of such weapons it was found, when the South’s shipyards fell to Federal troops, that the Confederacy had implemented an extensive building programme for “special attack” craft.