Roman legion

The Roman legion was the largest military unit of the Roman army, composed of Roman citizens serving as legionaries. During the Roman Republic the manipular legion comprised 4,200 infantry and 300 cavalry. In late Republican times the legions were formed of 5,200 men and were restructured around 10 cohorts, the first cohort being double strength. This structure persisted throughout the Principate and middle Empire, before further changes in the fourth century resulted in new formations of around 1,000 men.