All legionary soldiers also received a sizeable sum of money on the completion of their term of service: 3000 denarii from the time of Augustus and/or a plot of good farmland (good land was in much demand). Later, under Caracalla, the praemia increased to 5000 denarii.

So this is the army that conquered the “world”- a large force of disciplined men in tight ranks acting as one.  Almost nothing of the day could withstand this unrelenting fighting machine.