Carroballista was an ancient, cart-mounted ballista, a type of mobile field artillery. According to the Roman author Vegetius (Epitoma rei militaris II.25), each legion had 55 carroballistae which were arrow/bolt-shooter of the cheiroballistra type. Surviving representation of a carroballista are from the bas-reliefs of Trajan's Column (Scene XL and Scenes LXV/LXVI) and the Column of Marcus Aurelius.