Every unit of the Roman army, whether mounted or not, would depend in one way or another upon animals for its transport. Wagons and carts used to carry baggage would require animals to pull them. In some instances, oxen would pull wagons, as evidenced on Trajan’s Column. The word impedimenta implies the baggage train as a whole, comprising oxen, horses, asses, mules, the wagons and carts and their drivers as well. Iumenta refers to the actual animals of all types.