Late Roman Army (Fifth century)

[Artorius1960]

I'm not positive, but from things I've read, the field army instituted a new structure for the legion that made legions pretty much "battalion" sized units. The sub-division of the legion was the ordo of 200 men. Each legion contained 6 ordines.

Auxilia units were half the size of a legion and comprised 3 ordines.

This would be true for commitatensian and palatine units. I'm not sure how the limitatensian units were organized. They may have retained the older structure of the legions.

I don't have any evidence, but it's tempting to think of the legions operating tactically in groups of three ordines, which the size of auxilia might suggest. 1200 is a little unwieldy for a tactical unit and 200 is a little small.