Late Roman Legion size based on the Perge Inscription

[FlaviusB]

Hmm, maybe - although the evidence that we have (both literary and, for example, fort sizes) suggests that all units were getting smaller, not just the cavalry. 

But I think it's quite likely that the legions of the 2nd/3rd century had more than 120 cavalry. If you take a Flavian-era legion of 9 normal cohorts (each comprising 6 centuries of 80 soldiers, plus optio, signifer, centurion = 83 men) and one 'double sized' first cohort (comprising 5 centuries of 160 soldiers, plus optio, signifer, centurion = 163 men), and add a 'Josephan' 120-man cavalry complement you get 5417 men. But if you increase the cavalry by 2.5 to 300 men, the total is 5597; add the aquilifer and praefectus castrorum, and we're close to Suetonius's 5600. So perhaps even by his day the legions had more cavalry?

(alternatively, of course, Suetonius was just describing a legion with a larger century. Century size is one of the greater imponderables of all these calculations.)

I still don't think we can be certain about identifying the 'veredarii' with cavalry, of course. I'm also perplexed about the apparent clear division of their number into 9 subunits of 25 and one double unit of 50... Surely nothing like a 'Vegetian' milliary first unit could have survived into the army of the late 5th century? Or could it...?

My point about the Cavalry unit sizes is that if the Romans were still raising new units en masse, then raising smaller Cavalry regiments would provide some room for increasing the cavalry element of the newly reduced legions, assuming of course that they didn't already possess more cavalry than the notional 120 Equites Legionis. 

If my count is correct, the Notitia Dignitatum lists 99 Equites, 14 Cuneus and 10 Ala regiments in the Western Roman Army, and 117 Equites, 30 Cuneus and 73 Ala in the East; assuming an Ala of 512 and a Equites of 360, this means Cavalry regiment size was reduced by a third and the Legion size by two-thirds, so there would be some room to allocate more Cavalry to the smaller legions.