What if you weren’t a citizen?

Non-citizens (people from the conquered territories) could join the Auxilia, a supplemental fighting force made up mainly of cavalry and archery units. As a reward for joining, sons of serving members could become citizens and thus the Auxilia was an important tool for integrating newly-invaded territories into the ever-expanding empire.

Auxiliaries were never formed into full legions but remained as cohorts (roughly 500 soldiers). They usually exemplified the fighting strengths of their region of origin and, over time, became as important as the citizen legions of the Roman Army. Indeed, by the 2nd century AD, they made up almost three-fifths of the Roman Empire’s land army.