frontage of a consular army

[Michael Collins]

Would anyone like to estimate the frontage of a consular army (of 4 legions, just the infantry alone, not including the cavalry)?

I`d be interested to learn how varied the answers might be.

[Michael J. Taylor]

I've made some estimates for the infantry frontages in my article "Roman Infantry Tactics in the Mid-Republic: A Reassessment," based on the doctrinal frontages of Hellenistic forces in various battles (feel free to DM me with an email to request an offprint).

For the infantry frontages, between 350-500 meters for a 4200-5200 legion or similar sized ala. Total infantry frontage of a consular army (2 legions and 2 ala) would therefore be 1400-2000 meters.

Cavalry frontages are difficult, because cavalry formations themselves were more fluid. The 30 man turma seems best disposed to 3 files of 10 riders (8 deep was not uncommon for the Greeks). If we give each horse 2 meters, the, 600 Roman cavalry might take up 120 meters; allied cavalry varied, but let's just use 900 as a round number, so 180 for the allies: 400 meters total. But a lot more uncertainty here: less clear how much space per horse, how much space between formations, etc.

Still, very roughly a consular army needed around 1800-2400 meters (1.2-1.5 miles). Plenty of uncertainty, but the general magnitude is not implausible; you could certainly give the cavalry more room if you wanted. And many consular armies also had thousands of auxiliaries attached, which could extend the line even further.

Obviously, the army could narrow considerably if necessary, either by eliminating space between the maniples or by stacking units on top of one another; the consular army at Tunis in 255, for example, reportedly had a very narrow front--Roman tactics were flexible!

[Michael Collins]

Thanks Michael,
I was after a "standard" battle array, rather than the more exceptional deeper formations that are referred to as at Tunis/Bagradas and Cannae too. But yes, files or rather sub-units can be doubled and so the legion`s tactics were flexible.
Yes, the cavalry could perhaps be more flexible and indeed, why not have the turmae led/directed by the right?

[Mark Hygate]

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

[Michael J. Taylor]

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).

[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.

[Michael J. Taylor]

This would be an incredibly phalangeal legion. I would agree that 200 is a good rule of thumb frontage for the hastati--but Polybius implies more space between soldiers in combat, and then some space between the maniples. And I am quite open to the Roman pace being a useful tool for determining formation deployments (it is still used by modern soldiers today for drill and ceremony). So give each man five feet (2 paces, close to Polybius' somewhat mercurial 6) and 25 meters between maniples (10 paces), and you've got a legion at 1250 feet, c. 375 meters---my ballpark guess.

Certainly there are follow-on implications to any reconstruction of Roman tactics. But 2000 feet---c.650 meters, is a very small amount of tactical space for 16,000-20,000 men to cover. A standard Macedonian array, 16,000 phalangites, could cover nearly a kilometer (c. 3000 feet) in their default formation. And our sources indicate that the Romans often beat numerically superior forces--at Ilipa, Zama, Magnesia, Pydna etc., would would suggest that they had the ability to at least match opposing frontages rather than just getting enveloped and rolled up.

And note at Pydna, Livy suggests that a single Roman legion, here with a super-strength of 6000, was able to match a phalanx of c. 10,000 men (probably 10 chiliarchies). This suggests the legion could field a frontage of at least c. 1800 feet, c. 500 meters.

[Mark Hygate]

Understand all those points - and the previous discussions that support them. However, it's my belief that, having gone back to the original source and re-examined it (as mentioned before); that there is another interpretation - that, overall, might make more sense.

Firstly, I would re-emphasise a point I made several years ago now - that the 'open order' concept that Polybius seems to imply is, frankly, not practicable for the actual combat phase.  That believing that a Roman century 10-men wide in open order (each man with a 3ft gap between them - side-to-side and front-to-back) facing 20 close order 5-deep (the pikes that show forward, with the first 5 ranks ranks leaning forward, before they start to carry the pike almost vertically) could possibly resist the pike-phalanx - or even just a similar hoplite array (which stood equally shoulder-to-shoulder), is, I'm afraid, pretty non-sensical.  I have therefore become convinced that what Polybius describes was not the case for the actual combat phase when a closer order was necessary.

The epiphany moment for me was realising what 'the Triarii always number 600' actually meant.  The Triarii are still armed and armoured in a practically equivalent way to the preceeding Hoplite; presenting a shield-wall of spears behind which to retreat and re-group if necessary.  Deployed 200 men wide (single legion considered) and 3-deep (the practical limit for standard hasta/spears) and shield-spearshaft-to-shield (so 2.5ft/1 pace each) will occupy 500 feet/100 double-paces.

The Roman legion cannot therefore be any wider - otherwise the tactics just won't work.

The other thing I think you are not considering (and let's indeed posit a 'numerically inferior' force of a standard Consular Army just as you suggest) where a 3,072 ft full phalangial array (and they will have supporting troops) faces off against a 2,000 ft-wide (my interpretation) infantry portion of the Consular Army.  That there is an overlap doesn't necessarily result in the flanks being turned - because maintaining the phalanx's line remains paramount. If the pike-phalanx is disrupted and broken up (the exact result the Roman's are tactically organised to achieve and ernestly desire!) then it most probably loses.  So it won't just sweep forward.  In addition we haven't yet mentioned the supporting troops!  Lighter troops and cavalry are specifically required to protect and deny the flanks.  Lastly, whilst this, apparently over-whelming phalanx (1,024 men wide and 16 deep) has to maintain it's formation - the Romans have 3 separate lines of troops and great tactical flexibility.  It then comes down to manoevre and use of reserves.  It's the Romans that have the more tactically flexible force - but this sometimes wasn't enough...

It is my interpretation, but I do indeed reject the idea of gaps between heavy-infantry in the close battle phase, as I also do the idea of significant gaps between maniples at the same juncture.  They just don't make sense.  Maintaining the 'line' was a feature of warfare from the earliest organised proto-hoplite until the wide-spread introduction of the rifle.  Modest gaps to enable manoever, yes.

PS - and I believe the legion Livy describes is a full-strength 5,000 man legion, albeit described as being a 'full 60-centuries' after the later generic understanding that a century became equivalent to 100...

[Michael Collins]

"The Roman legion cannot therefore be any wider - otherwise the tactics just won't work."

I have come to the same conclusion Mark and this is why I posted the question.

[Mark Hygate]

"The Roman legion cannot therefore be any wider - otherwise the tactics just won't work."

I have come to the same conclusion Mark and this is why I posted the question.

Then I only need to try and convince you that 500ft might well be the answer!

Whilst your paper on the possible varying manipular gap based upon the opposing forces likely frontages given the common view of accepting said 'gap' made perfect sense from that point of view; I just don't believe that view.

I believe that the concept of leaving 'gaps' in your line to be a very dangerous one and only to be used when setting some sort of trap - indeed exactly what I think was done at Zama; which only worked because those gaps were masked until the trap was sprung.

I've come to the likely idea that the frontage of the Roman Legion was 500ft circa 300BCE and survived entirely unchanged for at least 500 years (whenever a full legion deployed) - which has lead me to not only an entirely plausible understanding of the triplex-acies and the manipular tactic, but then also a resulting idea on how later cohort tactics worked.

[Michael Collins]

"The Roman legion cannot therefore be any wider - otherwise the tactics just won't work."

I have come to the same conclusion Mark and this is why I posted the question.

Then I only need to try and convince you that 500ft might well be the answer!

Whilst your paper on the possible varying manipular gap based upon the opposing forces likely frontages given the common view of accepting said 'gap' made perfect sense from that point of view; I just don't believe that view.

I believe that the concept of leaving 'gaps' in your line to be a very dangerous one and only to be used when setting some sort of trap - indeed exactly what I think was done at Zama; which only worked because those gaps were masked until the trap was sprung.

I've come to the likely idea that the frontage of the Roman Legion was 500ft circa 300BCE and survived entirely unchanged for at least 500 years (whenever a full legion deployed) - which has lead me to not only an entirely plausible understanding of the triplex-acies and the manipular tactic, but then also a resulting idea on how later cohort tactics worked.

Unsure about 500 feet being right, but I`d agree with you on some other points you make here...

perhaps someone else wrote a paper on varying  manipular gaps?

[Mark Hygate]

My apologies - wrongly identified.

In addition - and I realised this whilst getting ready to collect Grandson...

There is at least one well known example when the 'frontage' was indeed, effectively, doubled - and that's dear old Arrian's array against a cavalry army.  Done deliberately to cover a greater frontage and done with doubling the spear/hasta-armed numbers of the legionnaires to face said cavalry and relying on less depth than normal given the lack of an opposing infantry force.

[Michael Collins]

Interesting, got a reference for that please Mark?

[Mark Hygate]

Interesting, got a reference for that please Mark?

Only 'Flavius Arianus - The Expedition Against the Alans' - the original and allowing for lots of Greek-equivalents.

[And apologies to both Michaels in this thread - I hadn't properly deduced that I've been replying to a different Michael.  :-(  I'm pretty sure its Master Taylor who published the thesis on manipular-gaps.]

[Michael Collins]

Yes, I have it now in an online translation.

No worries Mark, there are so many Michaels about!