Roman Legion in late Antiquity

[Mark Hygate]

I don't know the original text. Did Polybius really say, that the optio and the signifer have been supernumerarii?
Afaik, the camps just show 10 rooms plus the room for the centurio. This would mean 81 people per centuria.

No, Polybius doesn't say that specifically, but their roles are those of supernumeraries and they are detailed in the same section. I've studied it rather a lot and tried to make sense of the 4,000 and 4,200 men per legion figures - and one interpretation seems to make more sense than any other....at least to me.

That the '200' men that are often probably misinterpreted as being velites (thus many later authors using 1,200 as their figure) are in fact the total number of supernumeraries - being 60 Centurions, 60 Optios, 60 Signifers + 20 'others' (most likely Cornicen's that are otherwise missing, but we believe they must be there somewhere).

With that interpretation then we see the earliest incarnation of the 80-man century (60 Hvy Inf and 20 Velites (half that for small Triarii maniples)). The classic contuberniun/papillo (10of) contains 8 men as normal, as do the stone built equivalents, but the Centurion's tent, let alone the suite of rooms in stone barracks, has more than enough room for 3 (and an office-space).

Given the likely expected roles of the Centurion, Optio & Signifer the minimum number needed to control an 80 man century is 3 (as is the minimum platoon HQ section of the modern era). In the absence of any later information to give evidence against that figure, I see no reason not to assume a strength of 80+3 throughout the period (at full strength).