Roman soldiers were fighting men, first and foremost. Constant and rigorous training kept them at peak conditions, and ready for action at any time.
In the mid-Republic each Roman legion had an equivalent complement of allied infantry equipped and modeled after the legion and a three times larger complement of cavalry. The army of the Late Republic and Early to Mid-Empire consisted of legionaries and auxiliaries. The auxiliaries were named so after the earlier allied complement, but with structure and equipment differing from the legionaries. They were non-Roman citizens, recruited mostly from the Roman provinces with less pay than the legionaries, but at the end of their service they would be granted Roman citizenship. In the Late Roman army the distinction was between comitatenses, reserve troops and limitanei, border troops.