Quoting from the explanatory information about this cannon:
This US Civil War cannon was officially a Model 1857, light 12 pounder gun, popularly called a "Napoleon." Napoleon's were the most common and preferred canon of the Civil War by artillery men of both sides.
The 12 pounder designation means that an iron cannonball for this canon would weigh 12 pounds. Napoleon's were employed at ranges of up to 2000 yards.
The muzzle markings number 96, 1862 A. M. Co., 1223, and A. B. D. Tell us that it was the 96th gun made in 1862 by the Ames Manufacturing Company, that it weighed 1223 pounds and was accepted for the U.S. Army by ordinance officer Alexander B Dyer.The canon is located on the campus of Augusta University in Augusta, Georgia.