Originally posted by FistOfThe North
Didn't Rome occupy like the whole or most of Europe, about a fourth of Russia, the Mediterranean area and northern Africa/Carthage; areas almost twice the size of the U.S., with each area almost littered with the Roman Army?
Yes, they had a huge and expansive empire and they had about 375k soldiers at their disposal during the end of the height, this included both Roman and non-Roman troops they could draw upon, if Roman historian Edward Gibbon is correct.
Large contingencies of soldiers weren't needed to keep control of conquered populations. A small garrison was enough to keep those they conquered well aware of what would happen should they revolt, many a time. Sure the locals could uprise and kill the small group of soldiers, but in a few months they could expect a legion (or more) to come back and bury a sandal up their asses again.
Also, the worlds population was far far less back then, so 375k soldiers was more than ample.