The Heavy Mortar Cannon, or simply the Heavy Mortar, is a field artillery piece that has been part of the Imperium’s arsenal since the earliest years of the Great Crusade, and quite likely even the Unification War on holy Terra itself. In this distant past, the Heavy Mortars was used by both the troops of the Imperial Army and the Legiones Astartes, espacially those specialized in siegecraft such as the Iron Warriors. Today however, the Heavy Mortar is only used by the Imperial Guard’s siege companies, having been replaced by more sophisticated weapons. The weapon is a larger version of the standard mortar weapon used by most Imperial Guard forces. It is also the same weapon used on the Griffon self-propelled mortar tank. The weapon is classified as field artillery, which, unlike heavy artillery, is used close to the front lines in direct support of the infantry and vehicles that are already in combat rather than being fired from well behind the lines, usually in preparation for an assault. The Heavy Mortar’s primary advantages include its wide range of ammunition types, a high rate of fire, and its great simplicity to construct and maintain. The weapon is light enough to be easily towed behind a Centaur utility vehicle, and can be set-up or torn down quickly and moved either to safety or to get closer to the enemy as the Imperial lines advance.