Zodiac and Late Roman Army Organisation

[Robert Vermaat]

one can’t see those Palatina units as ‘auxiliaries’ anymore. They were, with the Scholae units, the core of the Imperial field armies, after all.

But surely Silvanus was in command of just such an imperial field army at the time? [..]The latin for Silvanus' command is octo auxiliarium milibus - not very helpful!

Yes, he commanded a field army, and I expect him to have commanded several comitatenses and even palatina units. But all of them?

[Flavivs Aetivs]

one can’t see those Palatina units as ‘auxiliaries’ anymore. They were, with the Scholae units, the core of the Imperial field armies, after all.

But surely Silvanus was in command of just such an imperial field army at the time? [..]The latin for Silvanus' command is octo auxiliarium milibus - not very helpful!

Yes, he commanded a field army, and I expect him to have commanded several comitatenses and even palatina units. But all of them?

It may be possible, depending on how well stocked the Limitanei garrisons were at that time. I don't have access to (Ammianus, I think) right now, so I can't check what they say about the state of the army under silvanius. But late on, Stilicho commanded the Entire Italian field army to fight radagasius, and Aetius the entire Gallic army and palantine troops to fight the goths, franks, burgindians in the 430s and the Huns in 451, but both of these armies were consdierably smaller than they would have been around the time of Silvanius and Julian.

So it's possible, but not plausible.

[Nathan Ross]

I expect him to have commanded several comitatenses and even palatina units. But all of them?

There are, I think, 65 auxilia palatina units listed in the ND as being under the total command of the Magister Peditum (which I'm assuming was Silvanus' post?). We can't hope to know quite who Ammianus' 'octo auxiliarium milibus' were, and they may indeed have been federates (or 'reserves', in a common but unhelpful translation!) of some sort - but since Silvanus was commanding an imperial taskforce fighting a barbarian incursion, I suspect they might have been regular Roman troops.

However, my point was merely that a force of 8000 could potentially have been assembled from 16 500-strong units, as it would have been under the principiate. Beyond that I wouldn't want to speculate too much!

[Renatus]

Robert wrote: Interesting. When Isidore fits your theory, you declare him trustworthy. When Vegetius doesn't, you suggest he's not?

I have never stated Vegetius is untrustworthy. I find it pointless making judgements about ancient historians. I was asking Renatus’ about his stance on Vegetius.

Renatus wrote: Well, you were the one who cited him in support of your theory.

I was just seeking your outlook on Vegetius. Nothing sinister intended. For the record I have no problem with Vegetius. I did once but that has been sorted out. I have no interest in labelling a source trustworthy or not. I am more interested in how they arrived at their figures.

The question of the merits and demerits of Vegetius would justify a thread of its own which would probably generate as much passion and dispute as this one. However, I will give my personal assessment.

I hold Vegetius in some regard and believe him to be an honest reporter of his sources. Of course, this immediately raises the question of the reliability of those sources but we will have to pass on that, as we can only surmise as to which of his named or unnamed sources provided any particular piece of information. Vegetius himself claims that he has put nothing of himself into his compilation but has only gathered and put in order scattered items of knowledge (Veg. 1.8.12). Strictly speaking, this applies only to Book 1, which he wrote independently of the others, and he may have allowed himself greater latitude in his later books. However, on the whole, I believe that he applied similar criteria throughout - except, that is, for Book 2. Book 2, in which he attempts to describe the ancient legion, including the numbers that are relevant to this discussion, is something of a shambles and he tries to absolve himself from responsibility by pleading the difficulty of the subject (Veg. 2.4.4). In my view, the explanation lies, first, in the limitations suffered by all ancient scholars that, lacking the modern advantages of speedy communications and networks of like-minded individuals sharing the fruits of their researches, they were confined to the material available in the localities in which they lived and worked. Secondly, he was hampered by the belief that the legion was an immutable body, largely unchanged since its inception, and that such changes as there had been were recent. Consequently, faced with differing descriptions of the legion at different stages in its development, he attempted to reconcile the irreconcilable and produced an impossible combination of elements from the Republic, the Principate and a period close to his own time. Amongst this muddle, is his attempt to reconstruct the numbers of the infantry and cavalry sections of his ancient legion (Veg. 2.6). This has all the appearance of a mathematical construct based on limited information. Underlying it is a belief in the 6000-man legion or, rather, a legion of at least that number which could be enlarged, if necessary (Veg. 2.2.3; 2.6.10). Even this is not established as, according to him, the legion actually numbered 6100 infantry plus 726 cavalry. Individual snippets of information may be accurate but, as a whole, it does not hang together, as Vegetius himself recognised (Veg. 2.4.4). In short, although I consider that, viewed in its entirety, Vegetius' work contains much of practical value (as demonstrated by its popularity amongst military men from the Middle Ages to the Enlightenment and beyond), when it comes to his description of the ancient legion and the numbers that go with it, he is wholly unreliable. I would not want to base any theory upon it.

[nikgaukroger]

It's often claimed that the auxilia units in the Late Roman army were only 500 men strong. If this is so then there is a real problem with this number as Silvanius took 8000 auxilliaries with him on a journey in Gaul according to Ammianus. Now, if these auxilliaries are not mercenary Franks then this would have added upto an astonishing 16 units of auxilia!!! I am more inclined to the idea of the auxilia units being around the 800-1000 man mark at that time, which gives a more credible 8 to 10 units accompanying Silvanius.

I'm not at all sure why you would view 8-10 units as being inherently more credible than 16.

[Flavivs Aetivs]

It's often claimed that the auxilia units in the Late Roman army were only 500 men strong. If this is so then there is a real problem with this number as Silvanius took 8000 auxilliaries with him on a journey in Gaul according to Ammianus. Now, if these auxilliaries are not mercenary Franks then this would have added upto an astonishing 16 units of auxilia!!! I am more inclined to the idea of the auxilia units being around the 800-1000 man mark at that time, which gives a more credible 8 to 10 units accompanying Silvanius.

I'm not at all sure why you would view 8-10 units as being inherently more credible than 16.

It's because of Logistical Demand - Assembling 8 units and supplying their needs is exponentially easier than assembling 16 and thier needs. It has to do with money, supply caravans, and how much of a strain it would put on the beauracracy. Orders from Rome to Trier could take 2 weeks if using the Circus Publicus (Based on Symmachus Journey from Rome to Trier and his letters), and by then those orders could be outdated.

[antiochus]

Mr Campbell wrote: 12 cohorts?! And different legions organised in different ways?!

No, there are not different legions organised in different ways but one legion organised in different ways. I’ve manage to identify a legion has three organisations. This trend began with the maniple legion. That is why I found for the battle of Ilipa, Polybius’ reference to one cohort and Livy’s three cohorts per wing conducting the outflanking manoeuvre are the same number of men. Polybius is relating to the higher echelon organisation and Livy a lower organisation. Both historians are correct. The problem is although the sizes vary in each organisational level, to confuse the issue, the primary sources call each differing organisational level a cohort.

Mr Campbell wrote: I'm not sure why you set such store by Isidore's evidence. We've already pointed out how unreliable he is.

You also pointed out the Theban legion is untrustworthy yet the numbers show a correlation to Isidore and Vegetius. In relation to Isidore’s military NUMBERS, no one has convinced me he is unreliable. However, when it comes to the third figure of 6585 men for the Theban legion, I will admit I have met my Waterloo. Two of the figures given for the Theban legion, plus Isidore and Vegetius have proven to me they are all reading from the same page.

Mr Campbell wrote: On the latter point, you are actually correct: his evidence does raise the question of "why 6000?" But that's a question that you must answer, as it's you who have decided to trust Isidore.

I’m confident my research will show that Isidore’s figure of 6000 can be trusted.

Renatus wrote: Amongst this muddle, is his attempt to reconstruct the numbers of the infantry and cavalry sections of his ancient legion (Veg. 2.6). This has all the appearance of a mathematical construct based on limited information. Underlying it is a belief in the 6000-man legion or, rather, a legion of at least that number which could be enlarged, if necessary (Veg. 2.2.3; 2.6.10). Even this is not established as, according to him, the legion actually numbered 6100 infantry plus 726 cavalry.

Thank you for your assessment of Vegetius. I have found Vegetius has made a simple mathematical mistake to arrive at the figure of 6100 due to his confusion regarding the various organisational levels of the legion.

[nikgaukroger]

I'm not at all sure why you would view 8-10 units as being inherently more credible than 16.

It's because of Logistical Demand - Assembling 8 units and supplying their needs is exponentially easier than assembling 16 and thier needs. It has to do with money, supply caravans, and how much of a strain it would put on the beauracracy. Orders from Rome to Trier could take 2 weeks if using the Circus Publicus (Based on Symmachus Journey from Rome to Trier and his letters), and by then those orders could be outdated.

How would the logistical demands of 8000 men in 16 units be "exponentially" greater than 8000 men in 8-10 units?

Not sure what the distance from Rome to Trier has to do with the plausibility of 16 units compared to 8-10 either - perhaps you could expand on that for me please.

[Renatus]

Thank you for your assessment of Vegetius. I have found Vegetius has made a simple mathematical mistake to arrive at the figure of 6100 due to his confusion regarding the various organisational levels of the legion.

I'd like your thoughts on that.

[Flavivs Aetivs]

I'm not at all sure why you would view 8-10 units as being inherently more credible than 16.

It's because of Logistical Demand - Assembling 8 units and supplying their needs is exponentially easier than assembling 16 and thier needs. It has to do with money, supply caravans, and how much of a strain it would put on the beauracracy. Orders from Rome to Trier could take 2 weeks if using the Circus Publicus (Based on Symmachus Journey from Rome to Trier and his letters), and by then those orders could be outdated.

How would the logistical demands of 8000 men in 16 units be "exponentially" greater than 8000 men in 8-10 units?

Not sure what the distance from Rome to Trier has to do with the plausibility of 16 units compared to 8-10 either - perhaps you could expand on that for me please.

Let's look at these demands:

The average Comitatensian Infantryman was paid 6 Solidi per Annum. Throw in Food, cost of supplying that food, and the cost of his armor and you're looking at 30 solidi per annum.

On Campaign, you had to Guard these supplies as they worked it's way towards the border - According to Heather's Empires and Barbarians, the cost of transport of materials over land increased literally exponentially the further you got away from the supply source. Transport by ship was easier and cheaper, but not all places were accessible by ship.

Therefore, it is more difficult to upply the men, so you have to be reasonable about that.

And another reason I have seen is that the Field Armies and Garrisons would settle down at their stations and wouldn't want to leave their homes or families to go on camapign.

[Sean Manning]

But the logistical requirements are constant for a given number of men. Soldiers don't eat more because they are stressed out from being around too many units of strangers who speak funny Latin! Calling more units together is a bit more paperwork, but by all accounts the Late Empire wasn't short of clerks, and the smaller the individual units the less effort is required to support them on the way (any town probably had enough food and shelter on hand for 500 men; a few thousand men would be more challenging).

Eight thousand soldiers unhappy about being called out are eight thousand soldners whether they are in 8 units ot 16.

(By the way, everything I have seen says that transport costs increased linearly with distance in preindustrial societies, not exponentially. A yoke of oxen eats the same amount of fodder whether its been walking for three days or three weeks).

[nikgaukroger]

Let's look at these demands:

The average Comitatensian Infantryman was paid 6 Solidi per Annum. Throw in Food, cost of supplying that food, and the cost of his armor and you're looking at 30 solidi per annum.

On Campaign, you had to Guard these supplies as they worked it's way towards the border - According to Heather's Empires and Barbarians, the cost of transport of materials over land increased literally exponentially the further you got away from the supply source. Transport by ship was easier and cheaper, but not all places were accessible by ship.

Therefore, it is more difficult to upply the men, so you have to be reasonable about that.

And another reason I have seen is that the Field Armies and Garrisons would settle down at their stations and wouldn't want to leave their homes or families to go on camapign.

But again, none of this is really any different whether you have 8000 men in 16 units or 8000 men in 8-10 units - it is the same number of men either way (although you'd have slightly more senior officers with the extra number of units).

[Flavivs Aetivs]

But the logistical requirements are constant for a given number of men. Soldiers don't eat more because they are stressed out from being around too many units of strangers who speak funny Latin! Calling more units together is a bit more paperwork, but by all accounts the Late Empire wasn't short of clerks, and the smaller the individual units the less effort is required to support them on the way (any town probably had enough food and shelter on hand for 500 men; a few thousand men would be more challenging).

Eight thousand soldiers unhappy about being called out are eight thousand soldners whether they are in 8 units ot 16.

(By the way, everything I have seen says that transport costs increased linearly with distance in preindustrial societies, not exponentially. A yoke of oxen eats the same amount of fodder whether its been walking for three days or three weeks).

you have to account for the transport of that fodder to those oxen too, and that fodder to those oxen, etc. etc.

So it does increase linearly, my mistake. But it is much more difficult. I'll try and pull up an old argument of mine in another forum.

[nikgaukroger]

(By the way, everything I have seen says that transport costs increased linearly with distance in preindustrial societies, not exponentially. A yoke of oxen eats the same amount of fodder whether its been walking for three days or three weeks).

I suspect the costs calculation has something to do with whether the draft animals have to pull their own feed-stuffs or get it supplied en route. If they have to pull their own as well as the kit and food of the soldiers there is a limit as to how far they can go before all they are pulling is their own food.

[Epictetus]

I think it is also relevant if the animals were switched or not. The people of Village A had to give animals to get the supplies to Village B, who then had to provide animals to get to Village C. I believe we have evidence from petitions to the Emperor that this is how it worked inside the Empire. Presumably they could do the same thing outside the borders, if the native conditions were favourable. In these cases, fodder for the draft animals would be minimal (or even nothing if it was the requirement of the civilians) in many settled areas.