The twelve-pound cannon "Napoleon" was the most popular smoothbore cannon used during the American Civil War. It was named after Napoleon III of France and was widely admired because of its safety, reliability, and killing power, especially at close range. In Union ordnance manuals it was referred to as the "light 12-pounder gun" to distinguish it from the heavier and longer 12 pounder gun (which was virtually unused in field service.) It did not reach the United States until 1857. It was the last cast bronze gun used by the United States Army. The Federal version of the Napoleon can be recognized by the flared front end of the barrel, called the muzzle-swell.