The Roman Army A to Z: triarius

triarius (m. pl. triarii)

Third line of legionaries in the pre-Marian Republican system, composed of experienced veterans who acted as a tactical reserve, kneeling behind the hastati and principes. They were not normally used in battle, hence the expression ad triarios redire. Livy 8.8.11; Polyb. 6.23. [Keppie 1984]