The M4A1 Mortar Motor Carriage was a vehicle utilized by Allied forces during World War II. The vehicle was a variant of the M2 Half Track, equipped with 81mm M1 Mortar. The mortar was intended to be fired dismounted from the vehicle, but could be fired in an emergency to the rear from a base inside the vehicle. The A1 modification allowed the weapon to be fixed facing forward and fired from within the vehicle.