H. L. Hunley sinks USS Housatonic off Charleston

Background. USS Housatonic was a Union screw sloop-of-war commissioned in 1862 and assigned to blockade duty in Charleston Harbor. The Confederate submarine H. L. Hunley, built in Mobile and shipped to Charleston in August 1863, had previously suffered fatal accidents. Horace Lawson Hunley, the vessel's namesake, died in October 1863 during a failed mock attack, so he did not command the February 1864 mission.

The Attack. At just before 9:00 p.m. on 17 February 1864, Housatonic was maintaining her station outside the bar when attacked by Hunley. The submarine struck the ship, and a later wreck survey observed that the spar deck "appears to have been entirely blown off," with the vessel sunk. Postwar accounts mention blue lights as prearranged signals, with a lookout on Housatonic reporting seeing one after the ship sank.

Aftermath. Following the sinking, Union forces surveyed the wreck, noting the spar deck was fifteen feet below water. Recovery efforts to raise Housatonic's guns were completed later in 1864. The submarine itself was lost with its crew. Archaeological findings suggest the explosion likely inflicted fatal damage on the vessel itself, killing the crew immediately.