Imperial Roman organisation

[D B Campbell]

The fact that the Spartans could not manage same depth files in their field formations is irrelevant.

But instructive.

That does not however prevent them having an ideal full strength structure of centuries of 80 men and all military logic would put those soldiers whose role was to act as a command group, (Centurion, Signifer and Cornicen) outside that as also would be the role of the Optio and Tessarius as supernumeraries at the rear of the century, as shown in virtually all diagrams of Roman Legions by such acknowledged (admittedly secondary) experts such as Adrian Goldsworthy and Peter Connolly.

As far as we know, the Romans did have "an ideal full-strength structure of centuries of 80 men" -- that's exactly what Hyginus tells us. However, neither he nor anyone else tells us how they deployed for battle.

Note that the Romans did not necessarily share your idea of "military logic". It might seem to make sense to have the "command group" stand apart from the rank-and-file, and the modern graphics that you refer to (which, iirc, are usually theoretical "parade formations", rather than "battle lines", aren't they?) are useful in allowing us to visualize what that might look like. But the few descriptions of fighting that we have indicate that some of those "command group" individuals (I'm thinking of centurions and standard-bearers) were quickly embroiled in the fighting. The natural conclusion would be that, far from standing apart, they actually stood in the front rank.

It makes no military sense to set up a theoretical "perfect" organisation deliberately containing gaps in the rank and file structure by counting the Principales amongst the full strength 80 men of each century.

This would only lead to gaps in the formation, if the formation were a rigid 10 x 8 block (as in the modern "parade formation" diagrams). I don't believe that any ancient army was ever capable of guaranteeing such rigid regimentation (hence, my Spartan analogy -- if anyone could do it, you'd've expected it to be the Spartans! :wink: )