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.

In the period before the Civil War, a U.S. Army light artillery battery was organized with four M1841 6-pounder field guns and two M1841 12-pounder howitzers.

[1] The field gun fired solid iron cannon balls in a flat trajectory to smash its targets[2] while the howitzer was designed to lob hollow shells into massed formations or fortifications.

[3] Napoleon III realized that mixing field guns and howitzers within an artillery battery caused the logistical problem of having to carry two types of ammunition.

An American military commission sent to Europe in 1855–1856 led by Major Alfred Mordecai wrote a report praising the new gun-howitzer[4] and the U.S.

[5] On 14 December 1856, the Ames Manufacturing Company received an order to produce a copy of the gun-howitzer, and on 25 March 1857 the Ordnance Department accepted delivery of one 1,187 lb (538 kg) piece for a cost of $546.02.

[8] One member of the 1855 American military commission was Captain George B. McClellan who became major general in command of U.S. forces in summer 1861.

[9] The Confederate States started the Civil War with its batteries largely armed with the M1841 6-pounder field guns and M1841 12-pounder howitzers found in Southern arsenals.

[11] On 10 July 1862, Confederate chief of ordnance Colonel Josiah Gorgas sent the Tredegar Iron Works plans for the 12-pounder Napoleon.

On 5 December 1862, General Robert E. Lee wrote to the Confederate Secretary of War James Seddon asking that most 6-pounder guns and some 12-pounder howitzers be melted down and recast as 12-pounder Napoleons.

In December 1863, Federal troops captured the copper mines at Ducktown, Tennessee, stopping all manufacture of bronze cannons in the Confederate States.

[15] The Model 1857 bronze 12-pounder Napoleon gun barrel was 72.15 in (183.3 cm) from the muzzle to the end of the knob and weighed 1,227 lb (556.6 kg).

The canister round weighed 14.8 lb (6.7 kg) and contained 27 iron balls that were 1.49 in (3.8 cm) in diameter or slightly smaller.

In 1864, U.S. Chief of Ordnance Brigadier General George D. Ramsay wrote, "No instance has occurred during the war ... of the 12-pdr bronze gun (the Napoleon) having worn out or of its bursting.

[22] The Napoleon fired the same ammunition and propellent charges as the M1841 12-pounder field gun, but its tube and carriage were 577 lb (261.7 kg) lighter than those of the older artillery piece.

The 1863 Confederate States Ordnance Manual recommended that the Napoleon's ammunition box carry 12 shot, 12 spherical case, 4 shell, and 4 canister rounds.

[1] General Barry pointed out that after the First Battle of Bull Run, there were only nine artillery batteries of mixed calibers available, drawn by 400 horses and manned by 650 men.

By strenuous efforts, in March 1862 when McClellan's Army of the Potomac took the field, there were 92 batteries containing 520 guns, 12,500 men, and 11,000 horses.

[31] As late as the Battle of Prairie Grove on 7 December 1862, fought in Arkansas, the Union forces employed 40 guns, but none of them were Napoleons.

On the same battlefield, the Confederate Army of Northern Virginia employed only fourteen Napoleons, compared to forty-four M1841 12-pounder howitzers, forty-three 10-pounder Parrott rifles, and forty-one M1841 6-pounder guns.

Artillery, Battery B, armed with six 12-pounder Napoleons,[36] was deployed in an exposed position near the Bloody Cornfield at dawn and suffered heavy casualties.

[31] In the Army of the Potomac at the Battle of Gettysburg, every bronze smoothbore on the field was a Napoleon except two 12-pounder howitzers in the 2nd Connecticut Light Artillery Battery.