Roman Legions Cross the Rubicon

The Roman legion was the largest military unit of the Roman army, composed of Roman citizens serving as legionaries.^¹ During the Roman Republic the manipular legion comprised 4,200 infantry and 300 cavalry.^¹ In late Republican times the legions were formed of 5,200 men and were restructured around 10 cohorts, the first cohort being double strength.^¹ 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.^¹