frontage of a consular army

[Mark Hygate]

Infantry only - 2x Roman + 2x Allied Legions (standard 'Polybius' Consular Army) 2,000 feet (Roman, of course).

But that would mean the average Roman legion was almost twice as deep as a Macedonian phalanx in close order (3 feet per man, 16 deep).

Not 'twice' as deep - a 'standard' (small/original) Polybian legion of 4,000 infantry (+200 'officers') most probably (my interpretation of how the Romans fought, but, I believe, entirely consistent) - deploying 200 men wide by 20 deep.  Each man occupies 2.5 ft - exactly one Roman pace - each legion exactly 100 double-paces.  Each legion occupies exactly 1/10th of a Roman mile.  Measuring a battlefield and choosing the deployment becomes really easy.

Moreover, the 2,000 ft width of the standard Consular Army is exactly the width (less the road) of the standard Consular Army camp built directly behind it.

Indeed it has become my belief that the two-century Roman maniple 20-men/50ft wide is designed specifically in mind to oppose a standard Macedonian-style syntagma of 256 men deployed 16x16 on a 48ft frontage.  Allowing for the light infantry component of the legion; the heavy Romans are only deployed 15 deep - albeit a 6-deep formation is enough (in theory and hence 'Pyhric' losses sometimes) to oppose the Pike-Phalanx.  The Romans, however, have a whole spare set of troops to rotate with!

I'd go futher, because of that belief, and suggest that the tactical genius(es) who came up with the maniplular-legion did so as a direct result of Philip's and Alexander's sucesses - ie towards the end of the 4th centure BCE - which does seem reasonably consistent with the sources.