Touch hole

Essential parts of a cannon:
1. the projectile or cannonball (shot)
2. gunpowder
3. touch hole (or vent)

Firing of a field gun of the early 17th century with a linstock

A touch hole is a small hole, through which the propellant charge of a cannon or muzzleloading gun is ignited. In small arms, the flash from a charge of priming held in the flash pan is enough to ignite the charge within. In artillery, priming powder, a fuse, squib, or friction igniter is inserted into the touch hole to ensure ignition of the charge.

The powder in the touch hole was lit either with a slow match or a linstock.

Spiking the guns

If a cannon was in danger of being captured by the enemy, its crew would "spike" the gun to prevent it from being used against them. This would involve hammering a barbed steel spike into the touch-hole, which could only be removed with very great difficulty. Spiking an enemy's guns could also be done to prevent counterattacks and protect ships during withdrawal, as in the case of the Ranger's attack on Whitehaven during the American Revolutionary War.