Fort Nelson, the Royal Armouries Museum of Artillery
The Crimean War of 1854 called for a mortar that could be easily transported but was of sufficient size, and therefore calibre, to lob a heavy projectile over the walls of the fortress of Sebastopol. Robert Mallet, a civil engineer, proposed such a mortar, built up in sections so that each could be transported separately and the whole erected within a few hundred yards of the target. The mortar was to sit on a platform comprised of three layers of heavy baulks of timber, this resting on a sloping bank of earth at an angle of 45 degrees. This meant that no bed was needed. The relatively small distance to the target meant that a light charge and a small chamber would suffice. Mallet's mortars were soon to be recognised as unsurpassable pieces of ordnance in respect of the weight of metal they were intended to throw and when constructed one did actually throw a shell of 2,400 lbs a distance of 1 miles. The heaviest shell fired weighed 2,986 lbs. Until this date mortars such as the long-range 13-inch ones employed by the French at the Siege of Calais in 1810, and the Lige 24-inch mortars of 7-tons used at the siege of the Antwerp Citadel in 1832 were the largest ordnance around.
PS There's one outside the RA Barraks at Woolwich.
