The final category of heavy infantryman in the Roman Legion of the mid-republican period (3rd and 2nd century BC). The Triarii were the veteran soldiers who formed the third and final line of the legion, arrayed in ten maniples of 60 men. Unlike the hastati and principes the Triarii were equipped with a long hoplite spear instead of the Pilum although otherwise they were armed in the same way as their colleagues with the Gladius and body shield. The Triarii spend most of the battle kneeling behind their shields waiting for combat. Only if the first two lines of the legion had been defeated would the triarii enter combat and this was normally a sign of a serious crisis.
The Complete Roman Army, Adrian Goldsworthy. A very good history of the Roman army from the early Republic to the end of the Empire.
How to cite this article:
Rickard, J. (20 December 2002 ), Triarii, http://www.historyofwar.org/articles/concepts_triarii.html