Mallet's Mortar Shell

Mallet’s Mortar was, unusually, designed by a civil engineer. Robert Mallet created it specifically for the siege of the Russian defences at Sebastopol during the Crimean War (1854–1856). The project was only funded thanks to the personal intervention of Lord Palmerston. Also unusually, the mortar had to be prefabricated to ease transport by sea and across rugged terrain.

The mortar shell was the largest diameter ordnance ever produced in Britain and remained among the heaviest shells even by 20th-century standards. It was designed to penetrate deep into enemy defences and destroy entire sections with a single strike. However, during testing and trials, it became clear that firing the weapon caused the bolts holding it together to fracture.

Only two mortars were ever produced.

Key information

• Mortar weight: 43 tons
• Shell weight: 1.3 tons
• Shell diameter: 0.9m (3ft)
• Rate of fire: One round per 15 minutes
• Range c. 2.5km