The rebel Confederate submarine H.L. Hunley, the first submarine in history to sink an enemy warship, is raised from a barge by a crane at the former Charleston Naval Base in North Charleston, South Carolina back in August 2000. A century and a half after the American Civil War - and nearly a decade and a half after the sub was raised - just why the Hunley and its eight-man crew never returned from its mission is a mystery, albeit one that scientists may be closer to resolving.
Monday marked the 150th anniversary of the February 17, 1864, mission in which the Hunley sank the Union ship Housatonic as the Confederate rebels desperately tried to break the federal blockade that was strangling Charleston. When the crew of the Hunley set off a black powder charge attached to a spar to sink the blockading Housatonic and killing five Union sailors, so did the Hunley.
The remains of the vessel - which was built in Mobile, Alabama, and brought to Charleston in hopes of breaking the blockade - were discovered off the coast in 1995.
Five years later, in August of 2000, cannons boomed and church bells rang as the sub was raised and brought by barge to a conservation laboratory in North Charleston. There, scientists have since been slowly revealing the Hunley's secrets.
An examination of the spar found it was deformed as if in an explosion. Scientists now believe the Hunley was less than six metres from the Housatonic when it sank, which means it may have been close enough for the sub's crew to have been knocked unconscious by the explosion - long enough that they may have run out of air before awakening.
For years historians thought the Hunley was farther away and that crew ran out of air before they could return to shore. Photo: AP