The Federal version of the Napoleon can be recognized by the flared front end of the barrel, called the muzzle swell.
Initially hand-powered by oars, it was converted after 6 months to a screw propeller powered by a hand crank.
The submarine was lost in a storm off Cape Hatteras on April 1, 1863 with no crew and under tow to its first combat deployment at Charleston.
As the Confederacy struggled against the North, it attempted to purchase one of the latest ironclads from France, Stonewall (later acquired by Japan after the end of the war).
[5] She was temporarily de-commissioned, stationed at a US Navy dock, until she was offered for sale to the Japanese government of the Tokugawa shogunate.