In Philadelphia, the U.S. Navy's first submarine, French-designed and called the Alligator, is launched

The U.S. Navy contracted French submarine designer Brutus DeVilleroi to build a submersible that could defend Union ships from the new Confederate iroclads. Launched by the Philadelphia firm of  Neafie & Levy after delays that saw DeVilleroi leave the project,  the 275-ton vessel was tubular, 30 feet long, and driven by oars when submerged at around seven feet with crew of twelve.  Accepted by the Navy and considered its first ever submarine, Alligator never saw active service and was lost in a storm off Cape Hatteras, North Carolina on April 3, 1863.  (By John Osborne)