The 20-pounder Parrott rifle, Model 1861 was a cast iron muzzle-loading rifled cannon that was adopted by the United States Army in 1861 and employed in field artillery units during the American Civil War. As with other Parrott rifles, the gun breech was reinforced by a distinctive wrought iron reinforcing band. The gun fired a 20 lb (9.1 kg) projectile to a distance of 1,900 yd (1,737 m) at an elevation of 5°. The 20-pounder Parrott rifle could fire shell, shrapnel shell, canister shot, and more rarely solid shot. In spite of the reinforcing band, the 20-pounder earned a dubious reputation for bursting without warning, killing or injuring gunners. The Confederate States of America also manufactured copies of the gun.

The M1857 12-pounder Napoleon or Light 12-pounder gun or 12-pounder gun-howitzer was a bronze smoothbore muzzle-loading artillery piece that was adopted by the United States Army in 1857 and extensively employed in the American Civil War. The gun was the American-manufactured version of the French canon obusier de 12 which combined the functions of both field gun and howitzer. The weapon proved to be simple to produce, reliable, and robust. It fired a 12.03 lb (5.5 kg) round shot a distance of 1,619 to 1,680 yd at 5° elevation. It could also fire canister shot, common shell, and spherical case shot. The 12-pounder Napoleon outclassed and soon replaced the M1841 6-pounder field gun and the M1841 12-pounder howitzer in the U.S. Army, while replacement of these older weapons was slower in the Confederate States Army. A total of 1,157 were produced for the U.S. Army, all but a few in the period 1861–1863. The Confederate States of America utilized captured U.S. 12-pounder Napoleons and also manufactured about 500 during the war. The weapon was named after Napoleon III of France, who helped develop the weapon.