High Imperial Roman army vs Late Roman army

[Timianus]

What I don't understand is the conflict in Heathers book between the numbers he assumes about the roman army in total and at Adrianopel. Ancient and modern historians estimate 400.000-600.000 soldiers for the roman army pre-Adrianopel. I trend to believe in the smaller 400.000. But Heather claims 600.000. This means authorized (normal) strength not real strength. Authors also assume, that around half of them were limitanei and the army was divided almost equally between East and West.

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However, Heathers huge army of overall 600.000 men and his small field armies of 2 x 10.000 men at Adrianopel does not match.

I find the numbers game to be very confusing, even aside from the paper vs real strength. Are we talking about limitanei or permanent field army? Do those figures reflect every unit that was on the payroll or active combat troops [not the same in this period. My understanding is that a lot of "official" positions were technically part of a military unit]?

That said, to me the actual numbers are not what is important; what is important is the actual effect the loss had. Whatever the exact numbers, based upon the Romans' inability to contain the Goths after this period, Theodisius' inability to defeat them decisively in battle, the very favorable terms of the subsequent treaty, and the heavy recruitment of goths and use of federates thereafter, there can be no doubt in my mind that whatever the actual numbers, the Romans lost a sizeable portion of their combat troops at Adrianople and that this loss had a significant impact on 1) recruitment; 2) their ability to protect the borders; and 3) Roman-Goth relations.

If Heather is right about his 20.000 men at Adrianopel, then something is wrong with the shiny and glorious empire without any major decay, he describes in the first chapter of his book.

That is a whole different topic.