On the evening of February 17, 1864, the Hunley slipped beneath the surface of Charleston Harbor. The crew jammed an underwater torpedo into the hull of the blockade ship U.S.S. Housatonic. The torpedo exploded, and the Housatonic sank within minutes.
It was the first time a submarine had successfully downed an enemy ship.
(See photos in the National Geographic magazine feature "Secret Weapon of the Confederacy." )
But something went terribly wrong aboard the Hunley, and the submarine never emerged from the harbor.
Soon after the sinking of the Housatonic, Scafuri says, the Union Navy tried to find the Hunley by dragging ships' anchors along the bottom of the harbor.
The effort failed, but an anchor may have struck the submarine, which could explain the broken glass in the tiny hatch's porthole.
The Hunley was found in 1995 by underwater archaeologists working for author Clive Cussler.
The crew's remains were removed and buried in an elaborate ceremony in Charleston in 2004. (Read "'Last Funeral of the Civil War' to Put Hunley Crew to Rest" [April 16, 2004].)
The discovery of the unsealed hatch is the first substantial clue in the 142-year-old mystery of the Hunley's sinking.
The warship had two small hatches, one at the bow and one at the stern. The rear hatch's locking mechanism was still in place, Scafuri says.
But pieces of the forward lock were found on the floor beneath the hatch, where Lt. George Dixon, the Hunley's commander, would have been stationed.
Dixon could not navigate the submarine with the lock in place, so he had to remove it at some point, Scafuri says.
"It was necessary if he wanted to look out the porthole or open the hatch and look around," Scafuri said.
Why Dixon or another crewmember didn't replace the lock is still puzzling, Scafuri adds.
It probably will be years before that riddle is solved, however. The investigators are conducting a meticulous examination of the Hunley.
"It'll be finished when it's finished," Scafuri said.
Willie Drye is the author of Storm of the Century: The Labor Day Hurricane of 1935, published by National Geographic Books.
Free Email News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
SOURCES AND RELATED WEB SITES