Argentoratum - how many roman lines?

[Erpingham]

If there are antepilani, there must be postpilani, and ditto (probably) hastati (principes?) and ordinum primis (ordinum posterior/secundis?)

But are we supposed to take these antiquarian terms literally, or is Ammianus, as you say, demonstrating his literary skills with a battlepiece proving he is au fait with the classics of the genre?

[RichT]

They're in my translation.

Where? You mean 'they' taking a-p, h and o-p to mean 'all the Romans'? That seems unlikely, but if that is your position you need to spell it out.

[Justin Swanton]

They're in my translation.

Where? You mean 'they' taking a-p, h and o-p to mean 'all the Romans'? That seems unlikely, but if that is your position you need to spell it out.

Oh yes, sorry, missed that part out by mistake. That's what you get for typing in a hurry at work.

[RichT]

If there are antepilani, there must be postpilani, and ditto (probably) hastati (principes?) and ordinum primis (ordinum posterior/secundis?)

But are we supposed to take these antiquarian terms literally, or is Ammianus, as you say, demonstrating his literary skills with a battlepiece proving he is au fait with the classics of the genre?

I have no idea, having no knowledge of the later Roman army, but I think that if Ammianus lists three particular groups of people it is because he means those groups, specifically. Whether he is using the correct names for them (and they were rather different from their Classical counterparts, as in the translator's hastati = standard bearers, ordinum primi = staff officers), or whether he is deliberately using archaic names to refer to familiar concepts (the vanguard, the leading units) I don't know, and don't know if anyone knows. But it seems unlikely that he just meant 'all the Romans'.

[Erpingham]

There's a small and mostly unhelpful RAT discussion of the castra praetoria at Argentoratum:
https://www.romanarmytalk.com/rat//printthread.php?tid=20560

Read that.  Doesn't help, as you say.

No other examples are offered. It does feel like an idiom but who knows?

I'm very tempted to think Ammianus is running off with his extended metaphor about walls and towers and he may intend the reader to think of the castra Praetoria and its relationship to the Roman walls.

[Erpingham]

I have no idea, having no knowledge of the later Roman army, but I think that if Ammianus lists three particular groups of people it is because he means those groups, specifically.

I don't know much about the late Roman army either but I do think he has chosen terms from the "front" part of Republican legions.  Whatever exactly he meant, he seems to want us to get the idea he is talking about the foremost parts of the Roman army and particularly the main infantry line - none of these are cavalry designations, AFAIK.  It does leave open the possibility that he envisages another part of the army behind these.

[LawrenceG]

"velut insolubili muro fundatis" = " fixed (plural) like an immovable wall (singular)"

Fixed is plural because it refers to the antisignati, hastati and ordines primi.

Whether it is the troops that are being likened to an immovable wall, or their fixedness being likened to the immovability of an immovable wall is a good question.

[Andreas Johansson]

By the time of the Second Punic War antepilani were no longer a thing - they belonged to the legion of the Latin War where the antepilani were the leves, hastati and principes, whilst the postpilani were the triarii, rorarii and accensi.

Hm? My understanding (originally from Duncan I think but Perseus agrees) is that pilani = triarii, and I don't believe I've ever heard of "postpilani". Neither has anyone else, judging by the Google results.

(And as a point of logic, the existence of "ante-X" doesn't necessarily imply the existence of "post-X", only of X itself.)

[Justin Swanton]

b

By the time of the Second Punic War antepilani were no longer a thing - they belonged to the legion of the Latin War where the antepilani were the leves, hastati and principes, whilst the postpilani were the triarii, rorarii and accensi.

Hm? My understanding (originally from Duncan I think but Perseus agrees) is that pilani = triarii, and I don't believe I've ever heard of "postpilani". Neither has anyone else, judging by the Google results.

(And as a point of logic, the existence of "ante-X" doesn't necessarily imply the existence of "post-X", only of X itself.)

Ok. I made up "postpilani" as a convenient term. "Antepilani" appears in Livy's description of the legion of the Latin War, and he affirms that the triarii, rorarii and accensii form a composite unit (ordo) that is behind the antepilani. History: 8.8. The pilus is the triarii but Livy makes clear that the antepilani are so-called because they are in front of the entire composite unit of which the triarii is only one subunit out of three. So to be exact the leves, hastati and principes are antepilani, the triarii are pilani and the rorarii and accensii are postpilani.

[Justin Swanton]

Re the infantry arrangement of the late Roman army, I think Vegetius is useful here. In De Re Militari, Book III, he seems to abandon his attempt at reconciling the multi-line legions of the Republican and Imperial eras in an anachronistic composite and simply describes the late Roman army as it actually was:

PROPER DISTANCES AND INTERVALS Having explained the general disposition of the lines, we now come to the distances and dimensions. One thousand paces contain a single rank of one thousand six hundred and fifty-six foot soldiers, each man being allowed three feet. Six ranks drawn up on the same extent of ground will require nine thousand nine hundred and ninety-six men. To form only three ranks of the same number will take up two thousand paces, but it is much better to increase the number of ranks than to make your front too extensive. We have before observed the distance between each rank should be six feet, one foot of which is taken up by the men. Thus if you form a body of ten thousand men into six ranks they will occupy thirty-six feet. in depth and a thousand paces in front. By this calculation it is easy to compute the extent of ground required for twenty or thirty thousand men to form upon. Nor can a general be mistaken when thus he knows the proportion of ground for any fixed number of men. But if the field of battle is not spacious enough or your troops are very numerous, you may form them into nine ranks or even more, for it is more advantageous to engage in close order that to extend your line too much. An army that takes up too much ground in front and too little in depth, is quickly penetrated by the enemy's first onset. After this there is no remedy. As to the post of the different corps in the right or left wing or in the center, it is the general rule to draw them up according to their respective ranks or to distribute them as circumstances or the dispositions of the enemy may require. DISPOSITION OF THE CAVALRY The line of infantry being formed, the cavalry are drawn up in the wings. The heavy horse, that is, the cuirassiers and troopers armed with lances, should join the infantry. The light cavalry, consisting of the archers and those who have no cuirasses, should be placed at a greater distance. The best and heaviest horse are to cover the flanks of the foot, and the light horse are posted as abovementioned to surround and disorder the enemy's wings. A general should know what part of his own cavalry is most proper to oppose any particular squadrons or troops of the enemy. For from some causes not to be accounted for some particular corps fight better against others, and those who have defeated superior enemies are often overcome by an inferior force. If your cavalry is not equal to the enemy's it is proper, after the ancient custom, to intermingle it with light infantry armed with small shields and trained to this kind of service. By observing this method, even though the flower of the enemy's cavalry should attack you, they will never be able to cope with this mixed disposition. This was the only resource of the old generals to supply the defects of their cavalry, and they intermingled the men, used to running and armed for this purpose with light shields, swords and darts, among the horse, placing one of them between two troopers. RESERVES The method of having bodies of reserves in rear of the army, composed of choice infantry and cavalry, commanded by the supernumerary lieutenant generals, counts and tribunes, is very judicious and of great consequence towards the gaining of a battle. Some should be posted in rear of the wings and some near the center, to be ready to fly immediately to the assistance of any part of the line which is hard pressed, to prevent its being pierced, to supply the vacancies made therein during the action and thereby to keep up the courage of their fellow soldiers and check the impetuosity of the enemy. This was an invention of the Lacedaemonians, in which they were imitated by the Carthaginians. The Romans have since observed it, and indeed no better disposition can be found. The line is solely designed to repulse, or if possible, break the enemy. If it is necessary to form the wedge or the pincers, it must be done by the supernumerary troops stationed in the rear for that purpose. If the saw is to be formed, it must also be done from the reserves, for if once you begin to draw off men from the line you throw all into confusion. If any flying platoon of the enemy should fall upon your wing or any other part of your army, and you have no supernumerary troops to oppose it or if you pretend to detach either horse or foot from your line for that service by endeavoring to protect one part, you will expose the other to greater danger. In armies not very numerous, it is much better to contract the front, and to have strong reserves. In short, you must have a reserve of good and well-armed infantry near the center to form the wedge and thereby pierce the enemy's line; and also bodies of cavalry armed with lances and cuirasses, with light infantry, near the wings, to surround the flanks of the enemy.

So what you have is the infantry in a single line, with reserve infantry behind the line on the wings and also the centre - but not a complete second line. Heavy cavalry flank the infantry and lighter cavalry flank the heavy cavalry.

This seems to be what Julian did at Argentoratum, with modifications. The legions deployed in a single line in the centre. On their right the Cornuti and Bracchiati deployed alongside them with the Batavii and the "Kings" behind them in reserve. On the left of the legions the Auxilia also deployed presumably with half in front and half behind in reserve. The Legio Primani may have been a reserve - "good and well-armed infantry near the center" - or Julian may have dispensed with a central reserve since he was badly outnumbered by the Alamans.

[Justin Swanton]

The Alaman deployment is interesting in that it closely mirrors the Roman system described by Vegetius. The Alaman infantry are in a single line with at least one reserve unit in the rear in a wedge shape which mirrors Vegetius' "you must have a reserve of good and well-armed infantry near the center to form the wedge and thereby pierce the enemy's line". The Alaman cavalry are mixed with infantry which mirrors "If your cavalry is not equal to the enemy's it is proper, after the ancient custom, to intermingle it with light infantry armed with small shields and trained to this kind of service". If imitation is the sincerest form of flattery, then the barbarians had had several centuries to become really impressed by the Roman military machine.

What is also interesting is the length of the Roman line as described by Vegetius. A rank contains 1,650 infantrymen which, at 3 feet per soldier, gives a width of 1500 meters. This is substantially wider than the Macedonian phalanx (1,000 meters) or the 4-legion Consular army (800 meters). It does explain where the extra infantry go once you remove the second and third support lines - keeping in mind Roman field armies of late Antiquity generally weren't any smaller than Consular armies of the Republican period so those infantry had to go somewhere. It is as wide as my proposed Roman infantry deployment at Cannae which seems to suggest that a 1,5km wide infantry line was about as wide as one could go and still act as a coherent body.

This would suggest that the late Roman army had a superior command and control system, able to routinely advance a wider line in a co-ordinated fashion without the line rupturing. Or it suggests that a shorter line wasn't a bad thing if support lines were there to counter outflanking.