Canister & Grape Shot

Canister was a thin-walled metal cylinder packed with musket balls, or large lead or iron balls, and sawdust. It was the artilleryman's most lethal load and probably killed more Civil War soldiers than all other types of artillery rounds combined. Depending on bore diameter, typical Civil War canister shot ranged from as small as .65 inch to as large as 2.25 inches in diameter. Some canister rounds have been found that were packed with nails, pieces of hinges, and other scrap metal — these improvised loads are known as Langrage.

A round wooden block, or sabot, was attached to the bottom of the canister to keep the round centered in the bore and to prevent propellant gases from escaping around the sides. When the powder ignited, the force of the explosion burst the thin can and the shot sprayed out of the muzzle with a murderous, shotgun-like effect.

Canister was only effective at short ranges — 400 yards or less for smoothbores. When the enemy was within 150 yards, crews would load two or even three rounds simultaneously ("double canister") and fire them all at once. Rifled cannon could also fire canister, but not as effectively: the smaller bores prevented the shot from dispersing as widely, and the balls could sometimes track along the rifling and acquire a spin.

The following table lists bore diameter, number of balls per round, and ball diameter for the major smoothbore cannon of the Civil War. Shot diameters are nominal; variations of ±.01 to ±.03 inch are commonly encountered on original specimens. Data compiled from the Ordnance Manual for the Use of Officers of the United States Army (J.B. Lippincott & Co., 1862).

Rifled cannon fired canister less effectively than smoothbores. The narrow bores restricted spread, and the spinning balls did not fan out as widely. Nevertheless, all standard field rifles were issued canister loads for close action.

Grapeshot was the predecessor of canister, originating as a naval round designed to cut rigging and sweep decks. By the Civil War, grapeshot was largely obsolete in field artillery — the period Ordnance and Gunnery manual states that grape was specifically excluded from "field and mountain services." It was, however, still used by garrison, seacoast, and naval batteries firing large-bore ordnance.

Army stands of grape typically consisted of 2 iron plates, 9 iron shot, a center bolt, and 2 iron rings. The shot were arranged in 3 layers, 3 balls per layer, with the bolt and rings holding the assembly together. The entire stand fell apart upon firing, spraying its large balls downrange.

Quilted grape was used primarily in the naval service. It was constructed with a base plate and an attached center post, with the shot stacked in layers around the post. A canvas bag was stitched around the shot to hold them in place and maintain a round shape. Stands of quilted grape carried 12 to 20 shot, in three or four layers of four, five, or six.

Depending on bore diameter, typical Civil War grape shot ranged from 2.05 inches to 4.55 inches in diameter — large enough to cause structural damage to wooden vessels as well as injury to crew members.

Canister parts are among the most recoverable artillery artifacts because individual balls, sabots, and iron plates survived combat while shells often exploded. Early relic collectors overlooked canister components, treating small iron balls as scrap. This makes complete assembled specimens exceptionally rare today.

The article "A Withering Hail of Iron" by Jack W. Melton Jr. — featuring the collection of David Gotter, winner of Best of Show at the 2018 Franklin Civil War Show — represents one of the most comprehensive published surveys of Civil War canister and grape specimens. The full article, with photographs of disassembled canister rounds and complete stands of grape, appeared in The Artilleryman.

When identifying recovered balls: iron canister balls were typically .65 to 2.25 inches in diameter; lead case shot balls were .5 to .7 inch; grape shot balls were 2.05 to 4.55 inches. Precise identification requires calipers and weight measurement against the shot tables above.

The figures on this page are drawn from the primary ordnance manuals of both armies. Photographs of original canister, stand shot and grape — together with the full bore and shot dimension tables — are elsewhere on this site.