- For other uses, see Cannon (disambiguation).
 A small cast-iron cannon on a carriage A cannon is a modern day rifled machine gun with a calibre of 20 mm or more (see autocannon).
Cannon also refers a large, smooth-bored, muzzle-loading gun used before the advent of breech-loading, rifled guns firing explosive shells.
"Cannon" derives from the Latin canna (a tube). Bombarde was early used for "cannon", but from the early 15th century came to refer only to the largest weapons. "Cannon" serves both as the singular and plural of the noun; "cannons" is generally considered incorrect.
History
The oldest evidence for the use of cannon is a relief carved by Buddhist monks in China in 1128, where a cannon is portrayed among other weapons of war. In the West, the use of cannon was first recorded in the battles of the early 14th century, for instance, at the siege of Metz in 1324, and by the English against the Scots in 1327. The earliest listing of firearms in an army inventory is in 1326. The new weapon's popularity is indicated by cannon being regarded "as common and familiar as any weapon" by 1350. The first cannon were of two types, small guns of cast bronze or larger, banded wrought iron cannon. Developments in gunpowder in the 1400s helped speed the military adoption of cannon. The actual effectiveness of these early weapons is not clear; battle reports of the time tend to exaggerate.
Early cannon did not always fire spherical projectiles. For smaller cannon, arrow-like rounds were used in the 14th century, sometimes with brass fin-stabilisers or inflammable heads. Initially, round shot was made of iron but was soon replaced by stone balls, particularly for larger pieces, due to the cost of metals in the 14th and 15th centuries. The round shot were sometimes covered in lead to reduce windage. For anti-personnel use, massed lead pellets were quickly adopted, but in extremis any small stones, nails, or iron scraps would be used as "hailshot".
The introduction of wheeled carriages for cannon did not occur until the 15th century. Prior to then the weapons were mounted on sturdy wooden frames. The largest siege bombardes would be strapped down to large timber baulks on earthwork platforms and aimed either with the initial platform or by hammering wedges under the front. Timber props supporting thick wooden planks were positioned to absorb the recoil.
 A Rodman cannon with its unique bottle shape In the 16th century the "Great Guns" were classified according to size, with such names as "cannon royal" (see Tsar Cannon), "demi-cannon", "culverin", "demi-culverin", "falcon", "falconer", "minion" etc., but by the 18th century they were classified by the weight of the round shot that they fired. Thus the demi-cannon was described as a 32-pounder (15 kg). Smaller guns included the 18-pound (8 kg) culverin, 12-pounders (5 kg), 9 pounders (4 kg) and 6-pounders (3 kg). The gun barrel was mounted on a wheeled carriage balanced on two "trunnions", the short metal projections on either side of the barrel invented by an unknown Dutchman. The angle of elevation could be altered by moving a wooden wedge under the rear end of the gun.
The early big guns were built up from strips of wrought iron, heated until they glowed yellow, and then hammered together to weld them and form the barrel. Rings of iron were forced over the barrel to reinforce it. Smaller guns were cast in brass or bronze, using techniques used for centuries to produce statues. In the 16th century the Dutch developed cast iron cannon.
The technique was imported into England, where the first iron cannon was cast in 1543. Iron casting reduced the weight and above all the cost of cannon to where they could be effectively mounted on ships, making cast iron cannon were one key element in England's growing naval supremacy.
In the 18th and early 19th centuries, cannon occupied several roles. On the battlefield they were like modern-day machine guns, used to "thin out" an advancing group of the enemy. In a siege, larger cannon and mortars were used more like conventional artillery or medieval siege weapons, to knock holes in the defenses.
The development of the smooth bore muzzle-loaded cannon culminated in the inventions of John A. Dahlgren, the admiral who designed the heavy, cast-iron cannon fired from Union ships in the American Civil War. In 1862 John Gilleland invented a double barreled cannon, which turned out to be a spectacular failure. The military use of cannon declined in the mid-19th century as fabrication technology improved enough to enable the rifling of gun barrels (which in turn required the introduction of breech loading) and the use of the far more destructive explosive shells.
Other large caliber guns (20 mm and up) were sometimes called "cannon". During the Second World War, the Royal Air Force fitted 20 mm Hispano cannon to its later model fighters. The Luftwaffe also used 20 mm and 30 mm cannon.
Projectiles fired from cannon
- Round shot
- A solid projectile made, in early times, from dressed stone but, by the 17th century, from iron. The most accurate projectile that could be fired by a smooth-bore cannon, used to batter the wooden hulls of opposing ships, forts, or fixed emplacements, and as a long-range anti-personnel weapon.
- Chain shot or bar shot
- Two sub-calibre round shot (a good deal smaller than the bore of the barrel) linked by a length of chain or a solid bar, and used to slash through the rigging and sails of an enemy ship so that it could no longer manoeuvre. Inaccurate and only used at close range.
- Canister shot (or case shot)
- An anti-personnel weapon which included twelve or so small round shot or lead musket bullets in a metal can, which broke up when fired, scattering the shot throughout the enemy personnel, like a large shotgun.
- Shell
- An anti-personnel weapon, similar to canister shot, but with a can that was much more robust and which also contained a fused explosive charge, trimmed to explode above the heads of the enemy, spreading shot and can fragments in the form of shrapnel over the enemy. First used in the 16th century as a siege weapon fired from mortars, and later as a battlefield weapon.
- Grapeshot
- An anti-personnel weapon, similar to canister shot, but with the shot being contained in a canvas bag, and generally of a smaller calibre.
Current status
 The large amounts of gunpowder make for a smoky mess. Operators hope for a calm day so they can continue to see their target. The caliber of a cannon, which is 20 mm minimum, has been a de facto standard since WWII, when heavy machine guns of 12.7mm (0.5") and 13.2mm caliber were used side by side with 20 mm and larger guns, which primarily used explosive ammunition. A modern artillery piece is generally referred to either as a "gun", or by the name of its specific type, such as a Howitzer.
In cases of emergency, ersatz cannon have been fashioned from objects as diverse as sewer pipes and hollow tree trunks, and in one instance even alligator carcasses1, as was described in the historical ballad, The Battle of New Orleans.
See also
Footnotes
1 "The Battle of New Orleans" (musical ballad), by Johnny Horton
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