Heated shot

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 hot shot dates back centuries and only ceased when vessels armored with iron replaced wooden warships in the world's navies. It was a powerful weapon against wooden warships, where fire was always a hazard. Its use 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. The French Romaine-class frigates originally also featured the device, but they proved impractical, dangerous to the ships themselves, and were later discarded.

The idea of setting fire to enemy warships can be traced back to the ancient world, where fire arrows and early incendiary materials such as Greek fire were used. In 54 BC heated clay balls were used by the Britons to attack Roman encampments, while in medieval siege warfare, catapults were used to hurl fire balls and other incendiaries into besieged castles and settlements.

The original method of heating round shot was to cover them in the coals of a large wood fire, or heat them on metal grates placed over a fire pit. These time-consuming methods were improved on by the French, who used specially constructed furnaces to heat shot in their artillery batteries at the mouth of the Rhône River in 1794. The United States incorporated hot-shot furnaces into the design of coastal fortifications during the construction of the Second System of seacoast defenses just prior to the War of 1812. Colonel Jonathan Williams left his post as Commandant at the US Military Academy to build hot-shot furnace fortifications such as Castle Clinton and Castle Williams in New York Harbor during this period. When French engineer General Simon Bernard came to the US in 1816 to head the Board of Fortifications, for the construction of permanent forts to defend the US coastline, he introduced the idea of hot shot furnaces of the French pattern. The chain of US seacoast forts built between 1817 and the American Civil War, such as Fort Macon, subsequently had one or more hot shot furnaces included as part of their standard defenses.

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