canister shot

• Illustration — Langrage shot for a cannon of the early 17th century, consisting of iron nails, iron fragments, loam, and hemp fabric, as a substitute for spherical metal projectiles. At times when the supply of balls were limited, nails, scrap iron or lead, wire, and other similar metal objects were included. The projectile had been known since at least the 16th century and was known by various nicknames in the 17th century such as hailshot or partridge shot. Rounds recovered from Henry VIII's warship Mary Rose (sunk 1545) were wooden cylinders filled with broken flint flakes. When filled with rubbish or scrap (rather than round bullets) the round could be known as scrapshot or langrage. In 1718, Blackbeard armed his guns with a range of makeshift weaponry including langrage. Several of his cannons, still loaded with spikes and shot, have been recovered from the wreck site of his flagship, the Queen Anne's Revenge. Archaeologists have also retrieved conglomerations of lead shot, nails, spikes and glass from the site. Langrage was also found among the artifact assemblage of the Mardi Gras shipwreck, 4,000 ft (1219 m) deep in the Gulf of Mexico.

When fired, the canister disintegrates and its shards and projectiles spread out in a conical formation, causing a wide swath of destruction. It was particularly effective during the Napoleonic Wars and the American Civil War, where massed troops at close range (usually less than 400 yards) could be broken up by artillery batteries firing canister. At times, particularly at very close range, artillery crews would fire extremely lethal "double canister," where two rounds were loaded into the gun tube and fired simultaneously using a single charge. At the Battle of Waterloo, in 1815, Mercer's Troop, Royal Horse Artillery, fired a roundshot and a canister from each gun as a double-shot. The roundshot was loaded first with the canister on top. Canister played a key role for Union forces during their defeat of Confederate troops in Pickett's Charge during the Battle of Gettysburg in July 1863. In 1864 at the Battle of Brice's Cross Roads the Confederates used this method. At times, trained artillerists would fire the canister shot towards the ground in front of advancing enemy troops, causing the conical pattern to flatten out as the balls ricocheted and skipped off the terrain. This in effect widened the killing zone. An example of this tactic was on the first day of Gettysburg, where Lt. James Stewart's Battery B, 4th U.S. Artillery on Seminary Ridge skipped canister shot at Alfred M. Scales's approaching Confederate infantry, breaking up their attack and forcing them to take cover in a depression. Canister shot was also used to good effect by U.S. Marine 37 mm anti-tank guns in World War II to break up Japanese banzai charges. During the Korean War United Nations tanks experienced close-range massed infantry attacks from Communist forces. As a consequence a canister-type tank round was introduced to "sweep" enemy infantry off friendly tanks without harming friendly tank crews, who were behind canister-proof armor. UK weapons known to have fielded a canister round are the 76 mm and 105 mm tank guns and the 120 mm MOBAT and WOMBAT recoilless anti-tank guns.

Shrapnel shells—named for the inventor, British artillery officer Henry Shrapnel—were developed from canister during the Napoleonic Wars and were intended to deliver the same canister effect, but at much longer ranges. As a result, its early designation was "spherical case shot". Instead of a tin can filled with metal balls, the shrapnel shells carry a small powder charge to break open the case and disperse the shrapnel. Grapeshot was a geometric arrangement of round shot packed tightly into a canvas bag and separated from the gunpowder charge by a metal disk of full bore diameter. Grapeshot used fewer but larger projectiles than were contained within canister or shrapnel shells. Case shot broadly describes any multi-projectile artillery ammunition. The canister round is known as a case, so canister was sometimes called case shot and the term has confusingly become generic for grapeshot and shrapnel shells. However, the term case shot is also used to describe a hollow ball containing a powder charge and bullets. After firing the iron ball the powder would explode, scattering the bullets.