Imperial Roman organisation

[Rod MacArthur]

Many sources for the Imperial Roman era give the strength of a century as 80 men and that of a cohort as 480 men. However, all my instincts are that these are rank and file figures, of the ten contubernia each of eight men in each century.

I would have thought that the total century strength would have also included the centurion, optio, tesserarius, signifer and cornicularis, bringing the total strength of a century to 85 and a cohort to 510.

There would be a parallel in the British Napoleonic era of showing all strengths as rank and file (corporals and privates) but needing to add officers, sergeants and drummers to these figures to arrive at an "all ranks" total.

Rod

[D B Campbell]

Many sources for the Imperial Roman era give the strength of a century as 80 men and that of a cohort as 480 men.

It is one source: the De munitionibus castrorum, traditionally attributed to Hyginus (probably incorrectly, so many refer to the author as Pseudo-Hyginus).

I would have thought that the total century strength would have also included the centurion, optio, tesserarius, signifer and cornicularis, bringing the total strength of a century to 85 and a cohort to 510.

Hyginus is describing how the imperial legion encamps, so he is concerned with actual strengths. (I'm assuming that we accept his evidence. If we don't, we're back to square one.) He says that the legionary centuria will require ten tents, each of which accommodates eight men (he doesn't call them a contubernium, by the way), but two of the tents needn't be pitched, as 16 men will be on sentry duty at any one time; hence, the space left from the two unpitched tents can be used for the centurion's tent.

Clearly, the centurion is not numbered amongst the 80, but the others (as promoted posts within the century) are.

[Rod MacArthur]

Duncan,

Yes, this clearly shows my inexperience in the Roman era. Most of my sources are secondary and I had failed to appreciate that there is really only one primary source (which I do not actually have). I am aware that it is also dangerous to attribute modern military practice (and even Napoleonic is modern in this context) to the Roman army, so my thought that the more junior officers in a century would not be counted in the "rank and file" would seem to be flawed.

Rod

[Macedon]

You are not that far off though. The thing is that the men of the rank, centurions included should logically abide by some specific arrangement rule that would make arithmetical sense. Yet, taking into account what was the usual rule in Greek and later Roman (Byzantine) armies where there is much more evidence, the supernumeraries should be excluded from this arithmetical rule and be counted extra (hence super-numeraries). Officers fighting in the ranks are not supernumeraries but any kind of musician, herald etc were not counted to the nominal strength of a unit. Was this also the case in Imperial Roman armies? Who knows... I would say it was but, of course, I cannot prove it and damn it, I am not good at Latin yet...

[Rod MacArthur]

It is one source: the De munitionibus castrorum, traditionally attributed to Hyginus (probably incorrectly, so many refer to the author as Pseudo-Hyginus).[/quote]

It occurs to me that there are other primary sources, namely archeological evidence. I therefore turned to my (secondary) source of the Osprey on "Roman Legionary Fortresses 27 BC - AD 378" to discover that you are actually the author.

On page 53 of your book you mention that some barracks had 12 pairs of rooms and one even 14. You speculated that it was possible that the extra space was allocated to the Principales (or junior officers) namely the signifer, optio and tesserarius (you did not mention the cornicen). This same point is made by Adrian Goldsworthy on page 86 of his "The Complete Roman Army" and by Graham Webster on page 197 of his "The Roman Imperial Army", both of whom stated there were normally at least 11 standard barrack rooms to a century. This is of course exactly the point I was making and would imply that these Principales were supernumerary to the 80 men in the rank and file of a full strength century.

In terms of tactical deployments Peter Connolly's diagram in "Greece and Rome at War" pages 217-218 show centurians immediately on the front right of their centuries, but not actually in the front rank, optios are at the rear and the tsserarius, signifer and cornicen are in front of each century. None of these posts are shown in the rank and file of the centuries. This is however a parade formation.

Ross Cowan's Osprey "Roman Battle Tactics 109 BC - AD 313 has a diagram on page 33 showing a pair of centuries in battle formation, one in close order and one in open order. In both cases the centurian and signifer are in the centre of the front rank with the cornicen in the second rank immediately behind the centurian. Both the Optio and Tesserarius are behind the rear rank as supernumeraries, and the note to the diagram mentions both had long staffs which could presumably be used to assist in pushing troops into formation (just like the late 18th century and early 19th century British sergeants halberds). Ross does mention that most reconstructions place the centurian on the right of his century, which was of course the traditional "post of honour", still was in battle formations of the 18th and early 19th centuries and still is in modern armies parade formations.

I also wonder about Hyginus description of a camp being prepared. I have not seen the original, but there is a summary in Webster's book. Although a centurian had comparatively palatial accommodation in a barracks I wonder whether he would not have had just a normal sized tent in the field, with a second normal sized one for the 3 or 4 principles, leaving 8 tents for the rest of the century (less the two contubernium on guard).

Bearing this in mind I do continue to wonder whether a full strength century was actually 85 personnel.

Rod

[D B Campbell]

On page 53 of your book you mention that some barracks had 12 pairs of rooms and one even 14. You speculated that it was possible that the extra space was allocated to the Principales (or junior officers) namely the signifer, optio and tesserarius (you did not mention the cornicen).

Tootling on the cornu was a function assigned to ordinary legionaries in return for immunity from fatigues. The cornicen was not a principalis and cannot be classified as a "junior officer" (a term I dislike). (As far as I am aware, it is not even clear whether each century was required to produce a cornicen, or whether they might be drawn disproportionately from one particular cohort, or whether they might simply have been drawn at random from the legion's manpower.)

This is of course exactly the point I was making and would imply that these Principales were supernumerary to the 80 men in the rank and file of a full strength century.

You've jumped a step! I see no reason to believe that the principales were supernumerary. Nor does the possibility that they might have been granted a little extra barrack space necessarily imply that their places were taken up by drafting in more men. If the current optio happened to have been promoted from your squad, it is equally likely (more likely, I would say) that your barrack room suddenly became a little less crowded. :wink:

In terms of tactical deployments Peter Connolly's diagram in "Greece and Rome at War" pages 217-218 show centurians immediately on the front right of their centuries, but not actually in the front rank, optios are at the rear and the tsserarius, signifer and cornicen are in front of each century. None of these posts are shown in the rank and file of the centuries. This is however a parade formation.

Sadly, no ancient source describes this for us. The diagram you refer to was Peter Connolly's opinion of how it might work. I do like these perfect chequerboard diagrams, but I'm afraid I don't believe that it worked that way in practice.

I also wonder about Hyginus description of a camp being prepared. ... Although a centurian had comparatively palatial accommodation in a barracks I wonder whether he would not have had just a normal sized tent in the field, with a second normal sized one for the 3 or 4 principles, leaving 8 tents for the rest of the century (less the two contubernium on guard).

Although Hyginus does not specify the size of the centurion's tent, he is pretty clear that it's only the centurion who benefits from the vacant two-tent-sized space, not the centurion and the principales. He is also pretty clear that "a full century has eighty soldiers" (plena centuria habet milites LXXX); the centurion was not a miles, but the principales were.

[Rod MacArthur]

Duncan,

I thought I would ressurect this topic, particularly because on re-reading it you have implied that I was suggesting that if a Roman soldier was promoted his space in the barrack room would be filled by a new recruit. I did not suggest that, nor is that what I believe.

In general I subscribe to the theory that the Imperial Roman Army recruited its legions in mass enlistments at set periods. This fits with descriptions of legions falling in strength over time and also makes sense in terms of unit cohesion, which I recognise as a former Lieutenant Colonel in the British Army. I realise that there were exceptions to this general practice, for example in 4 cohorts being diverted to replace those lost by 9th Hispania in the Boudiccan revolt, but the fact this is mentioned in ancient texts indicates that it was unusual.

If therefore the starting point is one of these enlistments, most of the soldiers due for discharge will leave, probably to a new military colony. Centurions seem to have moved around during their careers so many would have stayed. I would however suggest that the majority of the principales (Optios, Signifers and Tessararius) would be re-enlisted soldiers at that stage, as may some Centurions. I suggest that the balance of re-enlistments would form the first cohort, various specialist immunes and possibly provide the initial conturberium commanders. At this stage I would suggest it would be the aim to bring the legion up to its full strength from the new enlistment.

At that full strength starting point I would suggest that the archeological evidence of Roman barrack block structure points towards the Principles having one or two rooms allocated to them, in addition to those allocated to the ten conturberium each of 8 men. You actually say this in one of your own books. This would make a full strength century 84 men, including Centurion, Optio, Signifer and Tessararius, leaving aside the Cornicen.

Obviously as time goes by the Legion strength will drop and there will promotions from the latest enlistment into the Principales, but in my view that does not negate the general principle of the Legion's full strength structure. The Centurion and Principales had battle positions outside the formation of the century and it makes no military sense to include them in the calculation of the ideal number of men required for a block 10 files wide and 8 ranks deep.

Rod

[D B Campbell]

you have implied that I was suggesting that if a Roman soldier was promoted his space in the barrack room would be filled by a new recruit. I did not suggest that, nor is that what I believe. ... I would suggest that the archeological evidence of Roman barrack block structure points towards the Principles having one or two rooms allocated to them, in addition to those allocated to the ten conturberium each of 8 men. You actually say this in one of your own books. This would make a full strength century 84 men, including Centurion, Optio, Signifer and Tessararius, leaving aside the Cornicen.

It still sounds (to me, at any rate) that you want to have your 80-man century and your principales. This is what I disagree with. The principales are numbered amongst the milites.

In general I subscribe to the theory that the Imperial Roman Army recruited its legions in mass enlistments at set periods.

I'm afraid that I don't.

The Centurion and Principales had battle positions outside the formation of the century and it makes no military sense to include them in the calculation of the ideal number of men required for a block 10 files wide and 8 ranks deep.

Your conclusion doesn't necessarily follow from your premiss. (Even if you subscribe to the idea of "ideal numbers" -- which I don't. If not even the famously regimented Spartan battle-line could manage same-depth files, what chance did the Romans have? :wink: )

[Nathan Ross]

In general I subscribe to the theory that the Imperial Roman Army recruited its legions in mass enlistments at set periods.

Where are you getting this theory from?

[Rod MacArthur]

The Centurion and Principales had battle positions outside the formation of the century and it makes no military sense to include them in the calculation of the ideal number of men required for a block 10 files wide and 8 ranks deep.

Your conclusion doesn't necessarily follow from your premiss. (Even if you subscribe to the idea of "ideal numbers" -- which I don't. If not even the famously regimented Spartan battle-line could manage same-depth files, what chance did the Romans have? :wink: )

In all armies, whether ancient Ptolomeic, Roman, Napoleonic or modern, there were authorised establishments (ie the number of men and structure which were ideally desired) and actual field strengths, which were inevitably less.

The fact that the Spartans could not manage same depth files in their field formations is irrelevant. I am sure that the Romans would have had the same problem in the field. 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.

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. Such gaps will occur anyway with attrition from a great many causes, but there is no point starting with them. I doubt if even Cornicens were so counted but I will explore that in a separate post.

Rod

[Rod MacArthur]

In general I subscribe to the theory that the Imperial Roman Army recruited its legions in mass enlistments at set periods.

Where are you getting this theory from?

Nathan,

There is a thread on this very forum about Legion Reinforcements which examines that theory, following the publication of a number of books expousing it by Stephen Dando-Collins. Although the general consensus was that his books contain many errors, there were a number of forum contributors, paticularly including yourself, who subscribed to that part of the theory. You referred back to an earlier thread from 8 years ago, which had an interesting in-depth discussion of the matter.

I think you are right.

Rod

[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: )

[Rod MacArthur]

Duncan,

You have quoted the Spartan army. In return let me quote the Ptolomeic army, rather closer in time to the Romans.

My source is Nick Secunda, in his Seleuicid and Ptolomeic Armies 168 - 145 BC, Volume 2 - The Ptolomeic Army. He notes that the Ptolomies used files of 16 ranks. In his book he shows an organisational diagram on Page 9. This shows the basic tactical unit as a Semia (should be a circumflex accent over the e but I do not know how to do this on my i-pad) of 256 men (ie 16 files of 16 ranks) plus 7 officers and 4 staff. He says this was the equivalent of a maniple, although obviously larger. It is not 256 total but 267 total. Six of these plus more HQ staff formed a Syntaxis or Regiment.

Is it likely that the Romans produced full strength organisations which were tactically illogical compared to the Ptolomies?

I wrote modern British Army establishments on several occasions during my 30 years service. I have also researched the. Authorised Establishments for the entire British Army of the Napoleonic Wars from the original manuscript documents in the National Archives and published this as a pair of articles (18,000 words in total) in the Journal of the Society for Army Historical Research. In this process I discovered that many of the principles used by the Napoleonic era drafters of military establishments would be entirely familiar to soldiers today (although a distinguished academic with no military background, Sir Charles Oman, had completely misunderstood them in his classic book "Wellington's Army").

Some Principles of War, and military organisational theory are of an enduring nature. Just because one ancient source says there were 80 soldiers in a century is not proof that he was including posts which any army, of any era, would be treated as supernumerary by any military logic. Most British sources of the Napoleonic era gave unit strengths as Rank & File. (ie corporals and privates), not counting officers, sergeants or drummers, but without explicitly stating that that was the case. In my view it would be totally illogical for a theoretical full strength century of 80 men to be anything other than 10 files of 8 ranks, so one has to add the Centurions and Principales to that, as clearly indicated by the archeological evidence of barrack block layout. I must repeat that your own book, on Roman Legionary fortresses, rather confirmed my view of that structure.

Rod

[D B Campbell]

You have quoted the Spartan army. In return let me quote the Ptolomeic army, rather closer in time to the Romans.

It's not a time thing, Rod. It's a regimentation thing. You have asserted that the Roman army was so regimented that it required blocks of 80 men, over and above any "command group". My reply is that I don't agree. Neither the Ptolemaic army nor the Napoleonic army can prove how the Roman army functioned. I wasn't citing the Spartans as proof of the Roman system; merely as proof that a highly regimented ancient army doesn't require to be drawn up in symmetrical blocks.

Is it likely that the Romans produced full strength organisations which were tactically illogical compared to the Ptolomies?

Again, logic is in the eye of the beholder. I'm not an ancient Roman. I sometimes find it hard to understand their mind-set. (btw I wonder what Nick Sekunda's source for the Ptolemaic army is?)

[Nathan Ross]

There is a thread on this very forum about Legion Reinforcements which examines that theory, following the publication of a number of books expousing it by Stephen Dando-Collins.

Yes, the thread you mention concerns the legions of Caesar's day, when the old republican practice of en bloc mustering and disbandment was still in use. After the reform of the army by Augustus, however, this practice changed, and the imperial legion (as you have it in your post above) was a standing formation. Dando-Collins prefers to believe that the old system still applied, and goes on in his books, I understand, to 'explain' various aspects of Roman military history with reference to it. Unfortunately this contradicts all available ancient evidence on imperial recruitment practices, and everyone (as far as I know) who's ever written on the Roman army - it would therefore appear that Dando-Collins invented this theory himself! hock: