Ancient army numbers

[diegis]

How large were the largest Roman expeditionary armies?

Roman army numbers are also, I believe, commonly inflated. I've argued here, for example, that the figures of hundreds of thousands of men suggested for Trajan's Dacian campaigns are probably mistaken - the actual total for the force was more likely 50-60,000.

Well i think Romans was able to field actualy easily over 100,000 soldiers during Dacian wars (maybe not 200,000 as some says, but somewhere betwen)

And this because Trajan prepared the war for few years, the supply lines was relatively short (Dacian capital, Sarmizegetusa, was at i think less then 200 km from the Roman border), and Romans might even bring more supplies easily from Panonia, using the Danube fleet.
Moesia was anyway a fairly rich province too, regarding agriculture or so.

I do however think that Persian army that invaded Greece was not near as big as some Greek ancient chronicars said, it was hard to supply very big armies back then, at distance from their bases and concetrated in a kinda poor terrain