Imperial Roman Armies 1st. Cohort

[oldbob]

I'm very confused about the man power and who they actuality there, also how many Centuries 5 or 6?

[Duncan Head]

Any confusion may partly be because the first cohort seems to have been enlarged only under the Flavians, that is at some point in the later first century. Tacitus has a reference to events of 14AD mentioning 60 centurions in a legion, which implies that at that date all ten cohorts were the standard six centuries. Hyginus, writing probably some time in the second century, says that a cohort took up a space of 120 by 180 Roman feet; but the first cohort, being twice the strength - quoniam duplum numerum habet - requires a space of 120 by 360. The usual view was that the first cohort consisted of five double-strength centuries, giving the legion 59 centurions: but I'm not sure what the actual evidence is beyond what I've cited.

[oldbob]

Mr. Head; thank you for your reply.

[Paul Innes]

Perhaps in this period the 60th centurion would be the primus pilus then?  Just a thought.  It would make him the senior centurion in charge of sixty centurions (including himself) - almost a 'century' of centurions?  This would maybe appeal to the Roman mania for order and tidiness...

PS hi Oldbob!

[Patrick Waterson]

Interesting thought, Paul.

It is actually possible that an enlarged senior (first) cohort emerged in the late Republic, based on the following rather scanty information:

• in Sallust's Catiline, the eponymous anti-hero fights his last battle leading his ferentarii, who are a part of the legion but evidently first in and presumably considered the elite as Catiline fights with them.


• in Plutarch's Lucullus, the consul leads two cohorts into action ahead of his two legions.  Given the time period, these would appear to be ferentarii.  Note they have a first-into-the-breach shock role rather than a skirmishing one.


• at Pharsalus, Caesar's devoted centurion Crastinus leads '120  men from the same century' into action.  This suggests a double-sized century and hence a double-size first cohort (I do not buy the idea that Caesar mistakenly wrote 'century' instead of 'maniple').

If the above is really pointing the way I think it does, it suggests that the short-lived ferentarii of the 60s BC became the (enlarged) first cohort either around 60 BC or under Caesar's tutelage (some time between 58 and 48 BC).  Etymology is an occasionally useful guide, and one might in this instance suppose that ferentarii (literally 'bearers of burdens') would be a picked cohort to 'bear the burden' of combat.

The traditional cohort is generally considered to have  fielded 480 men, and the senior cohort 800.  Our old friend Vegetius (who incidentally lists 'ferentarii' among the lighter troops, which is curious considering their full-blooded cutting-edge-of-melee role in Sallust and apparently Plutarch) lists 1,105 infantry and 132 cavalry in the senior cohort and 555 infantry and 66 cavalry in the remaining nine cohorts.  This gives a total of 6,100 foot and 726 horse.

Vegetius also lists 55 centurions per legion rather than 60.  He explains as follows:

Having shown the ancient establishment of the legion, we shall now explain the names of the principal soldiers or, to use the proper term, the officers, and their ranks according to the present rolls of the legions. The first tribune is appointed by the express commission and choice of the Emperor. The second tribune rises to that rank by length of service. The tribunes are so called from their command over the soldiers, who were at first levied by Romulus out of the different tribes. The officers who in action commanded the orders or divisions are called Ordinarii. The Augustales were added by Augustus to the Ordinarii; and the Flaviales were appointed by Flavius Vespasian to double the number of the Augustales. The eagle-bearers and the image-bearers are those who carry the eagles and images of the Emperors. The Optiones are subaltern officers, so denominated from their being selected by the option of their superior officers, to do their duty as their substitutes or lieutenants in case of sickness or other accident. The ensign-bearers carry the ensigns and are called Draconarii. The Tesserarii deliver the parole [tessera = watchkeeping tablet] and the orders of the general to the different messes of the soldiers. The Campignei or Antesignani are those whose duty it is to keep the proper exercises and discipline among the troops. The Metatores are ordered before the army to fix on the ground for its encampments. The Beneficiarii are so named from their owing their promotion to the benefit or interest of the Tribunes. The Librarii keep the legionary accounts. The Tubicines, Cornicines, and Buccinatores derive their appellations from blowing the trumpet, cornet, and buccina. Those who, expert in their exercises, receive a double allowance of provisions, are called Armaturae Duplares, and those who have but a single portion, Simplares. The Mensores mark out the ground by measure for the tents in an encampment, and assign the troops their respective quarters in garrison. The Torquati, so denominated from the gold collars given them in reward for their bravery, had besides this honor different allowances. Those who received double were called Torquati Duplares, and those who had only single, Simplares. There were, for the same reason, Candidatii Duplares, and Candidatii Simplares. These are the principal soldiers or officers distinguished by their rank and privileges thereto annexed. The rest are called Munifices, or working soldiers, from their being obliged to every kind of military work without exception. Formerly it was the rule that the first Princeps of the legion should be promoted regularly to the rank of Centurion of the Primiple [centurio prim pili]. He not only was entrusted with the eagle but commanded four centuries, that is, four hundred men in the first line. As head of the legion he had appointments of great honor and profit. The first Hastatus had the command of two centuries or two hundred men in the second line, and is now called Ducenarius. The Princeps of the first cohort commanded a century and a half, that is, one hundred and fifty men, and kept in a great measure the general detail of the legion. The second Hastatus had likewise a century and a half, or one hundred and fifty men. The first Triarius had the command of one hundred men. Thus the ten centuries of the first cohort were commanded by five Ordinarii, who by the ancient establishment enjoyed great honors and emoluments that were annexed to this rank in order to inspire the soldiers of the legions with emulation to attain such ample and considerable rewards. They had also Centurions appointed to each century, now called Centenarii, and Decani, who commanded ten men, now called heads of messes [caput contubernii]. The second cohort had five Centurions; and all the rest to the tenth inclusively the same number. In the whole legion there were fifty-five. - Vegetius, Epitome Rei Militari II.7-8

Vegetius - if correct in this matter - indicates that there were five centurions to a standard (555-man) cohort, these presumably being the final 5 men and the decurions the other 50, leaving 500 rank and file.  This may reflect the (3rd century post-Severan) legion but perhaps not the Augustan legion, which is generally considered to be more along the lines of 480-man cohorts and an 800-strong 1st cohort.  In this presumed organisation, all centuries are 80 men strong except those of the 1st cohort, which are 160 strong.  Hence the 1st cohort is considered to have five double-strength (160-man) centuries and the other cohorts six 80-man centuries each.

As you will have noticed, this tallies neither with Vegetius nor Hyginius, each of whom has the senior cohort at exactly double the usual cohort strength.  Hence although a popular reconstruction it is not proven.

This leaves us with the Vegetian-inspired likelihood that the Imperial legion contained 5,500 men in nine 500-man and one 1,000-man cohorts, plus officers.  Whether this applied in the first century is an open question, as by Vegetius' own testimony Vespasian was still adding supernumeraries during his own reign.  However I do not think one can go too far wrong with a 5,500-man legion and 1,000-man first cohort, even in the 1st century AD - Corbulo, in Tacitus' Annals XV.10, takes 1,000 soldiers from each of his three legions to go to the rescue of Caesennius Paetus, suggesting that he may have picked the first cohort of each legion.

Hope that helps more than it confuses.

[Duncan Head]

One other source of evidence is legionary fortress layouts, about which I don't know very much. But see http://tinyurl.com/dyvgt9k which suggests the first cohort's larger barracks are identifiable in some Flavian fortresses.

I seem to recall from one of the standard works on the army - maybe le Bohec? - that inscriptions show at least one  legion with well over 60 centurions, some possibly being supernumeraries, so actual strength reports may not be as useful as one might think for the theoretical organization.

[dwkay57]

Following Duncan's comment about what archaeology can tell us, the Osprey book "Roman Legionary Fortresses 27BC-378AD" contains an interesting discussion on this topic. The conclusion it draws tends to support the concept of a 5-double century cohort during the early empire. Most other books I've read tend to agree with this.

[Patrick Waterson]

As does Vegetius, but with the refinement that rather than having double centuries per se, his first cohort has ten centuries paired under five Ordinarii, each of whom commands two centuries which have their own centurions.

It may be worth noting that if (as per Vegetius) Augustus added the Augustales to the Ordinarii, this would suggest that the Ordinarii, and hence the paired centuries they commanded, and by implication the double-strength first cohort, were in existence before his reign - had he introduced the double-sized first cohort he would presumably be noted as having added the Ordinarii to the legion.

[Duncan Head]

in Sallust's Catiline, the eponymous anti-hero fights his last battle leading his ferentarii, who are a part of the legion but evidently first in and presumably considered the elite as Catiline fights with them.

Oh, no! Ferentarii are light-armed troops. Varro says so, and Gellius, and Vegetius, and Tacitus contrasts them with heavy-armed. I see no reason why the word should mean anything different here. Catiline's army is called "unarmed brigands", latrones inermes, and though this is no doubt rhetorical the army was improvised and drawn in large part from the poor, so could expect to have more lightly-armed troops than "real" legions. That's why they open the combat first.

in Plutarch's Lucullus, the consul leads two cohorts into action ahead of his two legions.  Given the time period, these would appear to be ferentarii.  Note they have a first-into-the-breach shock role rather than a skirmishing one.

Plutarch's two speirai are probably the same as Appian's two telesin, and more likely to mean legions than cohorts in this case. Or so suggests Luke U-S at http://www.ne.jp/asahi/luke/ueda-sarson/Tigranocerta.html, and I suspect him of being right this time.

What is also interesting, though, is Luke's observation, which he's made on both ancmed and dbmlist in the past, that Caesar several times mentions multiples of eleven cohorts - "The only guards provided against all these contingencies were twenty-two cohorts, which were collected from the entire province by Lucius Caesar" (Gallic War VII.65); "Caesar ... detached ... at night eleven cohorts, with a like number of horse, under the command of L. Julius Paciecus" (Spanish War 3); "Within the three days the eighth legion came to him, and twenty-two cohorts of the new levies in Gaul" (Civil War I.18). Luke thinks some legions were moving towards an eleven-cohort model, and that might provide some sort of prototype for the enlarged first cohort.

However there often seem to have been various groups of evocati, veterans, volunteers, generals' personal praetorian cohorts and so forth hanging about as well outside the normal legionary structure, and that might account for some of these odd numbers of cohorts.

This may reflect the (3rd century post-Severan) legion but perhaps not the Augustan legion, which is generally considered to be more along the lines of 480-man cohorts and an 800-strong 1st cohort.  In this presumed organisation, all centuries are 80 men strong except those of the 1st cohort, which are 160 strong.  Hence the 1st cohort is considered to have five double-strength (160-man) centuries and the other cohorts six 80-man centuries each.

As you will have noticed, this tallies neither with Vegetius nor Hyginius, each of whom has the senior cohort at exactly double the usual cohort strength.  Hence although a popular reconstruction it is not proven.

Except in so far as Hyginus does specifically state that a century is 80 men, and therefore by implication (there being six centuries to a cohort, as Hyginus says and all the Imperial records of centurions' rank-titles bear out) 480 rank-and-file to the (normal) cohort. Legionary fortress barrack-layouts say the same thing for cohorts 2-10, of course.

The first cohort is much trickier and I don't think there is any general agreement on the exact strength. But I don't think any of the identified first-cohort barrack-blocks can fit 1,000 men.

This leaves us with the Vegetian-inspired likelihood that the Imperial legion contained 5,500 men in nine 500-man and one 1,000-man cohorts, plus officers.

Closer to "impossibility" than "likelihood" for any part of the first century, in my own opinion.

[Patrick Waterson]

Fair points, Duncan: ferentarii can remain light-armed, and irrelevant to any question of an enlarged senior cohort, although Catiline's vartiegated collection of dubious manpower is given at least the dignity of legionary organisation by Sallust.

I am less sure about Lucullus' troops at Tigranocerta, for in Lucullus 27.6 Plutarch writes:

"the first eagle came in sight, as Lucullus wheeled towards the river, and the cohorts [speirai] were seen forming in maniples [lokhous] with a view to crossing"

The translation leaves out 'kai taxin' [and his (leading) legion] after 'Loukullou' [Lucullus] - here Plutarch is clearly distinguishing between legions [taxeis], cohorts [speirai] and centuries [lochoi], so when he writes that Lucullus:

"... himself, with two cohorts [duo speiras], hastened eagerly towards the hill, his soldiers following with all their might, because they saw him ahead of them in armour, enduring all the fatigue of a foot-soldier, and pressing his way along." - ibid 28.3

I conclude he means cohorts, not legions; the 'soldiers' [stratioton = forces] following him would be the balance of the legions, i.e. the remaining nine cohorts in each.  Whether he truly ranged ahead with two cohorts or just led from the right of one legion and the left of its neighbour with them is not clear from Plutarch's description, but something distinguishes these cohorts from the remainder of their respective legions.

This does suggest elite 'first cohorts' already being used in a spearhead role in 69 BC, though it does not mention their size.

Hyginus' exactly-double-strength first cohort should by simple arithmetic be 960 men, i.e. too large for known first cohort barracks, but the fact that he indicates a camp sector exactly double that of a normal cohort suggests that perhaps we should not take the size of legionary fortress barrack-blocks as indicating a less-than-double-sized establishment for the first cohort.  Legions on permanent station might find commanders 'borrowing' men from the first cohort for various detached roles, not least bodyguarding, which would see them quartered elsewhere on a semi-permanent basis.

Luke's observations on the eleven-cohort arrangement are interesting, as it does suggest a move to the principle of a double cohort at the head of the legion: even if the spare cohort is provided as stiffening, the consistency of the arrnagment is intriguing.  One gets the impression that the eleven-cohort agglomerations were new or improvised legions; might we speculate that after their first few actions Caesar could 'rank' the cohorts so that the best two would be combined into the official first cohort of double strength?  He deploys ten-cohort legions at Pharsalus (at least he fields 80 cohorts in eight legions) and Pharsalus is where Crastinus is leading a double-strength - or at least noticeably overstrength - century.

I think we are [i.e. Duncan is] sorting out the wheat from the chaff.  And it does look as if a first century BC version of the double-strength first cohort is visible at least in outline.

[Duncan Head]

Hyginus' exactly-double-strength first cohort should by simple arithmetic be 960 men, i.e. too large for known first cohort barracks, but the fact that he indicates a camp sector exactly double that of a normal cohort suggests that perhaps we should not take the size of legionary fortress barrack-blocks as indicating a less-than-double-sized establishment for the first cohort.

The evidence for the not-quite-doubled first cohort does indeed come from only a few fortress sites, so is perhaps less than overwhelming. My own gut feeling is that legions were perhaps not as uniformly organised as we generally assume - particularly under the warlords of the late Republic, but perhaps in the Empire as well. So I could conceive of an army where some legions had a 960-man first cohort, but others (XX V.V. or whoever at Inchtuthil) had five 160-man centuries.

Or it might be that a first cohort of 800 men was standard in the 80s when Inchtuthil was built, but 960 in the 2nd century when Hyginus probably wrote. Not really enough data to be certain, yet.

[Patrick Waterson]

Not a bad working hypothesis, though. 

That or the 1st century legate customarily borrowing a century on an extended basis as his personal guard - perhaps this equates to the guards mentioned by Josephus?

[oldbob]

Duncan and Patrick; thank you both for taking the time to reply.I know this subject has been kicked around before, bur it's such an intriguing subject to me.

[dwkay57]

If we're suggesting that the 1st legionary cohort was not always "milliaria" in the sense of 5 double centuries, what does that mean for the auxiliary milliaria cohorts?
Does that imply they also might be different in theoretical size?

I always considered the early Imperial Roman army to be somewhat consistent in organisation, but this discussion might suggest not. It would seem strange to organise differently when typically everything else about the way the army operated was highly consistent.

[Duncan Head]

Well, XX Palmyrenorum milliaria equitata is over 1,000 strong in two strength reports, apparently under six centurions - so, maybe yes!

http://www.academia.edu/2972630/The_Vindolandatablet_88_841_and_the_cohors_I_Tungrorum_milliaria is  interesting on the conversion of a cohort from quingenary to milliary.