The submarine H. L. Hunley was privately built in the spring of 1863 in the machine shop of Park and Lyons, Mobile, Ala., under the direction of Confederate Army Engineers, Lt. W. A. Alexander and G. E. Dixon, 21^st Alabama Volunteer Regiment, from plans furnished by Horace L. Hunley, James R. McClintock and Baxter Watson.

H. L. Hunley was fashioned from a cylindrical iron steam boiler as the main center section, with tapered ends added, and expressly built for hand-power. She was designed for a crew of 9 persons, eight to turn the hand-cranked propeller and one to steer and direct the boat. A true submarine, she was equipped with ballast tanks at each tapered end which could be flooded by valves or pumped dry by hand pumps. Iron weights were bolted as extra ballast to the underside of her hull; these could be dropped off by unscrewing the heads of the bolts from inside the submarine if she needed additional buoyancy to rise in an emergency. H. L. Hunley was equipped with a mercury depth gage, was steered by a compass when submerged, and light was provided by a candle whose dying flame would also warn of dwindling air supply. When near the surface, two hollow pipes equipped with stop cocks could be raised above the surface to admit air. Glass portholes in the combings of her two manholes were used to sight from when operating near the surface with only the manholes protruding above the water. Her original armament was a floating copper cylinder torpedo with flaring triggers which was towed some 200 feet astern, the submarine to dive beneath the target ship, surface on the other side, and continue on course until the torpedo struck the ship and exploded.

After successful trials under Lieutenant Dixon in Mobile Bay, General Beauregard ordered railway agents on 7 August 1863 to expedite H. L. Hunley to Charleston for the defense of that city. She arrived in Charleston on two flat-cars and under the management of part-owners, B. A. Whitney, J. R. McClintock, B. Watson and others unknown. B. A. Whitney was a member of the Secret Service Corps of the Confederate States Army, his compensation to be half the value of any Union property destroyed by torpedoes or submarine devices.

Finding the intended target, Union blockader New Ironsides, in too shallow water for the submarine to pass beneath her keel, the torpedo-on-a-towline was abandoned in favor of a spar torpedo which was a copper cylinder holding 90 pounds of powder and equipped with a barbed spike. The submarine would drive the torpedo into the target by ramming, back away, and by a line attached to the trigger, explode the charge from a safe distance. The submarine was based at Battery Marshall, Beach Inlet, Sullivan's Island, in Charleston Harbor where smooth waters of interior channels were particularly favorable to the operations of the under-powered submarine which could at best, make only about four knots in smooth water.

H. L. Hunley was soon given to a volunteer crew of Confederate sailors commanded by Lt. J. A. Payne, CSN, of CSS Chicora.

After several dives about the harbor on 29 August 1863, the submarine moored by lines fastened to steamer Etiwan at the dock at Fort Johnson. The steamer unexpectedly moved away from the dock, drawing H. L. Hunley on her side and she filled and went down. Five seamen of the CSS Chicora were officially reported to have drowned but Lieutenant Payne and two others escaped. The submarine was raised, and on 21 September 1863, turned over to Horace L. Hunley for fitting out and manning. He brought a crew from Mobile which had previous experience in handling the submarine and was to be headed by Lt. G. E. Dixon, 21st Alabama Volunteers, CSA.

In the absence of Lieutenant Dixon, 15 October 1863, Hunley took charge of the submarine for practice dives under the Receiving Ship Indian Chief. After several successful dives, the submarine again went under Indian Chief but air bubbles traced the downward course of the submarine which failed to surface. Hunley and his entire crew of seven lost their lives as the water was nine fathoms deep and nothing could immediately be done to aid them.

H. L. Hunley was raised and reconditioned by Lt. G. E. Dixon and Lt. W. A. Alexander but General Beauregard refused to permit her to dive again. She was fitted with a "Lee spar-torpedo" and adjusted to float on the surface, being ballasted down so that only her manholes showed above the water. For more than 3 months the submarine went out an average of 4 nights a week from Battery Marshall, Beach Inlet, Sullivan's Island. Steering compass bearings taken from the beach on Federal ships taking anchor for the night, she failed time and time again because of circumstances: the distance of the closest blockader often 6 to 7 miles away, the conditions of tide, wind and sea, or physical exhaustion of her crew who sometimes found themselves in danger of being swept out to sea in the underpowered craft.

Then on the night of 17 February 1864 she found her destiny in the Federal steam sloop-of-war Housatonic anchored in about 27 feet of water some 2 miles from Battery Marshall in the north channel entrance to Charleston Harbor. Approaching silently through calm waters, H. L. Hunley made a daring attack in bright moonlight and approached within a hundred yards of the blockader before Housatonic's lookouts spied the Confederate craft. By the time observers determined she was not a log or other harmless object, she was so close that the heavy guns of Housatonic could not be depressed sufficiently to come to bear. She approached the keel of her victim at right angles and came under small arms fire from the watch officers and men of the Housatonic.

Housatonic slipped her cable in great haste to try to back away. Her maneuver proved vain as H. L. Hunley's torpedo struck home under water just abaft the mizzenmast. There was a stunning crash of timbers and a muffled explosion like the report of a 12-pound howitzer and a severe shock. Some of Housatonic's crew reported pieces of timber hurtling to the top of the mizzenmast itself while a dark column of smoke rose high in the sky. Housatonic, in shallow water, settled rapidly to the bottom as all her crew, save five who were killed by drowning or explosion, scrambled to the safety of the rigging which remained above the water's surface.

H. L. Hunley failed to return from her mission. The exact cause of her loss is not known; she may have gone down beneath Housatonic; or in backing away, been swamped by waves caused by her sinking victim; or she may have been swept out to sea. In giving their livesthe heroic crew wrote a new page in history—the first submarine to sink a warship in combat—and cast a shadow far ahead to the enormous new power of sea-power in undersea war