The 1,000 man legion

[Robert Vermaat]

I don't want to derail the thread, but could this reduction not be due to the incredible stresses of supplying 600,000 troops.

Mobile units could be split up and billeted more efficiently in towns and cities. Limitanei units could be placed on the frontier in more discrete units and told to supply themselves to some degree. Neither of those things are really achievable with 5,000 man legions.

Maybe so. In fact, we see the creation of a mobile defense in depth force as a replacement of the large legions that occupied the borders before. To retain both would surely have been beyond the abilities of the Roman army and the economy.