The Confederate States of America used submarines in combat. They built small, steam-powered submarines, called Davids, named for the Bible's legendary giant-slayer. On Oct. 5, 1863, one of these attacked the USS New Ironsides off the coast of Charleston, South Carolina, disabling but not sinking the ship with a 65-pound spar torpedo.

The Civil War also saw the first submarine to successfully sink its target, the  40-foot-long Hunley , which was operated by eight men turning a hand crank attached to her propeller shaft. The Hunley sank and was recovered three times during trial runs before it was successful. On Feb. 16, 1864, under the cover of darkness, the Hunley sank the USS Housatonic off Charleston. Accounts differ as to the reason, but the Hunley sank soon after sinking the Housatonic . It was discovered in May 1995 off the coast of Charleston and was recovered in August 2000.

In 1861, French inventor Brutus De Villeroi convinced the Union Navy that he could build a submersible warship. On May 1, 1862 the 47-foot-long, oar-propelled Alligator became the first submersible warship of the U.S. Navy. Her first mission was to destroy a bridge and clear obstructions on Virginia's Appomatox and James Rivers, respectively. Unfortunately, neither river was deep enough to allow the Alligator to submerge and she was returned to the Washington Navy Yard. Her next challenge soon came: destroy the new Confederate ironclad, the Virginia II . However, test runs in the Potomac River proved the Alligator was underpowered, unwieldy, and unsafe. The plan was abandoned .

In 1863, after the Alligator's oar system was replaced with a screw propellor, the submarine was sent to help capture Charleston, South Carolina. While being towed south for the battle, the Alligator had to be cut loose during a storm off Cape Hatteras, North Carolina. Her current whereabouts are unknown, but an effort (launched in 2003) by the Office of Naval Research and NOAA could one day reveal the Secrets of the Alligator.

Launched in 1862 during the Civil War, Alligator was an engineering marvel that helped usher in a new era in undersea travel. But until recently, little was known about the green, 47-foot-long Union vessel. The Alligator was lost off the North Carolina coast during a storm in 1863. It was never seen again.

I magine living in Philadelphia during the early days of the Civil War and reading the latest issue of the Philadelphia Evening Bulletin. A front page story reveals a strange and alarming tale: Harbor police have captured a partially-submerged, 33-foot long, cigar-shaped contraption moving slowly down the Delaware River.

This "infernal machine," as the paper described it, was the creation of French inventor, Brutus De Villeroi. Whether a deliberate publicity stunt or not, DeVilleroi succeeded in convincing the Union Navy that he could produce a submersible warship from which a diver could place an explosive charge under an enemy ship. Six months later, in November 1861, he was under contract to build the Union's first submarine.

Hence begins the little-known story of United States Submarine Propeller U.S.S. Alligator -- a technological wonder akin to other great maritime advances of the Civil War era, including the well-known ironclad USS Monitor , and the recently-raised Confederate submarine, CSS Hunley .

Built in Philadelphia, the 47-foot long Alligator was primarily intended to counter the threat of the Confederate ironclad, the Virginia. Although the Navy specified that the submarine's construction take no more than 40 days at a cost of $14,000, the project suffered long delays. As project supervisor, DeVilleroi delayed completion by making changes during the process of advancing the initial design to an operational Naval vessel. As a result of serious liaison problems with the Navy, the contractor and himself, he effectively exited from the process and was later officially dismissed.

About a month after its launch on May 1,1862, the oar-propelled submarine was towed to Hampton Roads, Virginia. Her first missions: to destroy a strategically important bridge across the Appomattox River and to clear away obstructions in the James River.

When the Alligator arrived at the James River, with civilian Samuel Eakins in charge, a fierce battle was being waged in the area. Because neither the James nor the Appomattox was deep enough to permit the vessel to submerge, it was feared that even a partially visible submarine would be vulnerable to seizure by the Confederates. The Alligator was sent to the Washington Navy Yard, for further experimentation and testing.

In August 1862, Lt. Thomas O. Selfridge accepted command of the submarine, after being promised promotion to captain if he and the Alligator 's new crew destroyed the new Confederate ironclad, the Virginia II . During test runs in the Potomac, the Alligator proved to be underpowered and unwieldy. During one particular trial, the sub's air quickly grew foul, the crew panicked, and all tried to get out of the same hatch at the same time--prompting Selfridge to call the whole enterprise "a failure." He and his crew were reassigned and the vessel was sent to dry dock for extensive conversion. The dream of using this "secret weapon" against the Virginia II was scrapped.

Over the next six months, the Alligator 's system of oars was replaced by a screw propeller. In early spring 1863, President Lincoln observed a demonstration of the "improved" vessel. Shortly thereafter, RADM Samuel Dupont ordered the Alligator , once again commanded by Eakins, to participate in the capture of Charleston.

Towed by the USS Sumpter , the unmanned Alligator left Washington for Port Royal on March 31, 1863. On April 2nd, a fierce storm forced the crew of the endangered Sumpter to cut the submarine adrift, somewhere off the Cape Hatteras coast. According to reports sent to Secretary of the Navy Welles, the Alligator was "lost" at sea.

The Alligator was the first submarine to:

Be ordered and built for the U.S.Navy.
Have a diver's lockout chamber
Be deployed to a combat zone.
Have onboard air compressors for air renewal/diver support.
Be commanded by a U.S. Naval officer (who would later achieve Flag rank).
Be designed with an air purifying system.
Have an underway test witnessed by a U.S. president.
Have electrically-detonated limpet mines.
Undergo an overhaul in a U.S. naval shipyard.