Heated shot or hot shot is round shot that is heated before firing from muzzle-loading cannons, for the purpose of setting fire to enemy warships, buildings, or equipment. The use of heated shot dates back centuries. It was a powerful weapon against wooden warships, where fire was always a hazard. It was rendered obsolete in the mid-19th century when vessels armored with iron replaced wooden warships in the world's navies. Also at around the same time, the replacement of solid-iron shot with exploding shells gave artillery a far more destructive projectile that could be fired immediately without preparation.[1]
The use of heated shot was mainly confined to shore batteries and forts, due to the need for a special furnace to heat the shot, and their use from a ship was in fact against Royal Navy regulations because they were so dangerous, although the American ship USS Constitution had a shot furnace installed for hot shot to be fired from her carronades.[2] The French Romaine-class frigates originally also featured the device, but they proved impractical, dangerous to the ships themselves, and were later discarded.[3]