Developed for The Crimean War, The Mallet Mortar never saw combat. The Mortar was designed by Englishman Robert Mallet in 1854. The weapon was able to fire 4 shells per hour (factoring loading time). Requiring an 80-pound charge, The Mallet was capable of deploying a 2,500 pound shell 1.5 miles - in 23 seconds! It has a 26-inch bore diameter and it's barrel is 11 feet long. Only two such prototypes were built.