It was one of the Civil War’s most technologically advanced weapons. The H.L. Hunley was a 40-foot submarine built out of iron and powered by a hand-cranked screw propeller. The Confederate vessel secured its place in history on Feb. 17, 1864, when it set off 135 pounds of black powder along the hull of the USS Housatonic and became the first submarine to sink an enemy ship in battle. The Hunley and its eight crew members were lost to the waters off the coast of Sullivan’s Island that cold night, and five from the Housatonic were also killed.