The Canon obusier de 12 (French:'Canon obusier de campagne de 12 livres, modle 1853', USA: 12-pounder Napoleon), also known as the 'Canon de lEmpereur' was a type of canon-obusier (literally 'Shell-gun cannon', 'gun-howitzer') developed by France in 1853. Its performance and versatility (it was able to fire either ball, shell, canister or grapeshot) allowed it to replace all the previous field guns, especially the Canon de 8 and the Canon de 12 as well as the two howitzers of the Vale system.
The cannon owes its alias to French president and emperor Napoleon III.
This type of 'canon obusier', commonly called in English the '12-pounder Napoleon Model 1857', was the primary cannon used in the American Civil War. Over 1,100 such Napoleons were manufactured by the North, and 600 by the South. At Gettysburg, 142 out of 360 Federal guns (36%) were Napoleons.
The '12-pounder Napoleon' was widely admired because of its safety, reliability, and killing power, especially at close range. It was the last cast bronze gun used by an American army. The Federal version of the Napoleon can be recognized by the flared front end of the barrel, called the muzzle swell. Confederate Napoleons were produced in at least six variations, most of which had straight muzzles, but at least eight cataloged survivors of 133 identified have muzzle swells.