H. L. Hunley

The Confederate States most successful submarine was the H L Hunley

They actually refer to the same vessel, the complete name was the CSS H.L. Hunley. This Confederate submarine attacked the USS Housatonic and sank it before sinking itself with a loss of all hands.

The Confederate submarine H L Hunley sank a Federal warship, Housatonic

The H. L. Hunley was the name of the Confederate submarine that was the first combat submarine to sink an enemy ship.