* The standard British artillery pieces of the period – 6- and 9-pounders – were smooth-bore and fired either roundshot (solid iron balls) or grape (a larger quantity of smaller balls); the more destructive 12- and 24-pounder howitzers were rifled and fired the exploding shell (hollow projectiles packed with gunpowder and bullets) developed by Colonel Henry Shrapnel in 1803. For sieges the British used 18-pounders (also firing solid balls) and two types of mortar: 5½-inch and 8-inch. Most of this heavy ordnance – particularly 8-inch mortars, 18-pounders and 24-pounder howitzers – was available to the rebels at Cawnpore.