legions
Augustus established the military system which lasted until the third century. The army was composed of two parts (and there was also a considerable fleet). The senior part was a citizen army of some thirty legions (about 165,000 men), each commanded by a senator of middling status, and subject to the more senior senatorial governors of the imperial and senatorial provinces. Gradually these legions became a permanent feature of the frontier areas in which they were established. They recruited mostly from those areas. Although some legions changed their bases, such moves were not overall very frequent. Rather more numerous were the auxiliary troops who from the reign of Claudius regularly received the citizenship on discharge. The legionary army always remained part of the citizen body of Rome. Its communities, especially in non-citizen areas, enjoyed privileges like other citizen settlements, and expected the facilities-aqueducts, amphitheatres, baths and so on-of any classical city. (Boardman, 1986)