In a famous incident at the Battle of Antietam, Brig. Gen. John Gibbon jumped off his horse and raced over to Battery B, 4th U.S. Artillery, whose men were firing canister as fast as they could at Confederates across the Hagerstown Pike.
Gibbon noticed the battery’s 12-pounder Napoleons were firing high, and he directed the gunners to lower their muzzles so the canister would skip off the ground and up into the gray ranks. The adjustment was made, and the next blasts caused a grotesque plume of fence rails and Confederate soldiers to rise into the air.
Canister and its forerunner grapeshot were the most fearsome artillery projectiles of the conflict. Each fired iron balls into the air like giant shotgun blasts that shredded oncoming infantry formations and swept the decks of ships. Though the terms are often used interchangeably, as they were even during the war by soldiers, they were made quite differently. And by the Civil War, grapeshot was seldom used by field artillery batteries in either army, but some large garrison and ship-mounted cannons still made use of that round.
It’s hard to imagine how charging troops could bear down on an opposing battery, knowing that iron hail could strike at any moment.
The standard canister shot for the 12-pounder Napoleon consisted of 27 1.5-inch canister balls packed in sawdust, though this example contained more. The tin can disintegrated upon firing, dousing attacking infantry with the shot. At times, cannoneers even fired double canister. (The Minnesota Historical Society)
The stand of grapeshot on the far left was “quilted,” meaning iron balls were stacked around an iron pin, and then covered with cloth that was laced to hold the balls in place. By the Civil War, most grapeshot was made of iron plates and rings bolted together to keep the round intact. Canister was much easier to produce in comparison. (Heritage Auctions, Dallas)
The 12-pounder Napoleon, top, had a bore of about 4.6 inches across, and such smoothbore cannons excelled at firing canister. Rifled cannons, like the 3-inch Ordnance Rifle pictured above, could also fire canister, but not as effectively. The smaller 3-inch bores prevented the shot from dispersing as widely. The canister rounds could sometimes track along the rifling and pick up a spin, another reason the canister balls would not spread out over a wider area. But that fact would have been cold comfort to troops charging rifled artillery. (Photos by Melissa A. Winn)
Private Michael Dunn of the 46th Pennsylvania lost both his legs to canister at the May 23, 1864, Battle of New Hope Church, Ga. Canister was most effective up to 200 yards, but could also be deadly at 400 yards, maximum range for this projectile. (Library of Congress)
Smith Groom of Troy, N.Y., invented this shell to help rifled cannons fire canister. The rocket was supposed to fly downrange as a fuze, located in the brass tube inserted in the base, burned. After detonating, it was to scatter its “war missiles,” as Groom called canister. The prototype shell never went into production. (Heritage Auctions, Dallas)