The bow (ehrmm...CRESCENT) at Cannae

[RichT]

Indeed and this could all lead into a 'purpose of depth' discussion which would sail ominously close to the 'O' word. Bottom line is that although we don't really know why depth was useful for all sorts of forces that definitely didn't physically shove their comrades, such as cavalry, the fact is that it was, and cavalry formed deep because there was some advantage in doing so.

[Imperial Dave]

absolutely and only mentioned the O word for clarity that we weren't talking about massed ranks of cavalry only ranks of cavalry supporting each other in some other way 

[Justin Swanton]

although here I think we have to clarify whether we means multi-ranks to give relief/support or 'othismos' type momentum

You give me little choice but to invoke the Strategicon again ...

As we've discussed in various O-word threads, Maurice notes that unlike infantry, rear-rank cavalrymen cannot push on the ranks in front. Nevertheless, he insists that cavalry needs to be at least five ranks deep - albeit noting that in the good old days when men were real men and goats were nervous, four was enough - and that weaker units need more ranks, up to ten.

He also insists that it be employed in multiple lines, at least two and preferably three, so he sees utility in total depths of up to thirty ranks.

(Even greater line depths have been advocated by others; Nicephorus Phocas would have his cataphracts - who were surely not in any sense weak troops - twelve deep, and in the Northern Seven Years War Swedish regulations called for cavalry to be no less than fifteen deep, irrespective of quality.)

As for the purpose of the depth, the 2nd to 4th ranks can, Maurice implies, reach the enemy with their lances, as well as shoot effectively. This, of course, may not be very relevant to Cannae, where cavalry had no bows, and, I believe, rather shorter spears than what Maurice is implying (a lance that can reach past three ranks of horses is pretty damn long!). The later ranks, he makes it sound like, are mostly there to have somewhere to put men who are not up to fighting at the front. This is presumably not the whole story - if it were, why bring these guys along at all?

I had the tacticians in mind in that a few ranks are necessary (I think they also advocate 5) but more than that didn't achieve much. Methinks cavalry ranks were capable of charging and then countermarching back, allowing the ranks behind them to charge in turn. Aelian gives a description of the Roman cavalry using this tactic to throw javelins but it could have worked just well with contact weapons. In this context a few ranks are required to keep the conveyor belt going, but many ranks don't add an advantage. Maurice's multiple lines would have acted rather like a mounted triplex acies - if the front line was outfought and fell back, the second line could take up the fight, and so on.

Just adding extra ranks wouldn't of itself have helped the Carthaginians much against the Roman left flank cavalry. The Carthaginians needed to envelope the Romans which implies separating them from their infantry.

[Chris]

Interesting reading!   

Content to snack on dried kale chips from the cheap seats. 

[Erpingham]

Interesting reading!   

Content to snack on dried kale chips from the cheap seats. 

A decidedly healthy option.   UK vegetable crisps tend to be made of root veg, like parsnips and beetroot.

[Andreas Johansson]

I had the tacticians in mind in that a few ranks are necessary (I think they also advocate 5) but more than that didn't achieve much.

Aelian mentions "square"* formations with depths of three, four, and five, but doesn't say if those are the only ones that should be used. He spends more time on rhombus and and wedge formations, whose maximal depth is much greater. (It apparently never occured to the ancients to use hollow wedges.)

He's no help at all on what rear ranks were actually good for, sounding rather like even the 2nd is useless.

Asclepiodotus says that Greek cavalry was typically eight deep, but feels that three or four is better, because "the depth of the cavalry unit, providing that it is enough to hold the squadron firm and in line, does not have the same importance as in the infantry". Apparently then, at least part of the point to depth was to aid formation keeping. He too discusses at some length rhomboidal and wedge formations of much greater maximal depth.


* Horses being rather longer than wide, Aelian's square's have two or three times as many files as ranks. He also mentions, but doesn't discuss, formations that are "squares in terms of numbers", i.e. the same number of ranks and files. Asclepiodotus OTOH prefer to reserve "square" for formations of equal ranks and files, while ones square in shape are "oblong".

[Justin Swanton]

It's been a very quiet day at work so let me take some time to look at the sources a bit more closely.

Polybius states the Romans had 8 Roman legions and 8 allied legions at Cannae, giving a strength of 80,000 men.  Livy quotes a strength of 87,200 men (Livy 22.36). Polybius affirms that the legions deployed with their units (speira) with a depth 'many times' (πολλαπλάσιος) their width. The speira could refer to the maniple or century. I posit that the maniple's default deployment consisted of two centuries side by side, giving it a width of 20 men and a depth of 8 (including velites)*. For it to become many times deeper than wide, one would probably have to halve the width and double the depth of each century, making them 5 men wide and 16 deep, and place the centuries one behind the other, creating a unit 5 men wide and 32 men deep.

A standard Consular army of 4 legions would have a deployment width of about 800 yards - 200 for each legion (20 yards per maniple each consisting of 2 centuries deployed 10 x 8 once the velites were withdrawn) Quadrupling the number of legions but reducing by 3/4 the width of each legion leave you with a frontage that matches that of a normal Consular army - 800 yards.

Against this Hannibal deployed about 4,000 - 6,000 Spanish, 16,000 Gauls and 8,000 Libyan heavy foot. Even if the Libyans did not front the Roman foot (they did - see below), that means that the combined Gallo-Spanish line was 800 yards wide. If each file is a standard yard wide that gives a depth for the line of a least 20,000 / 800 = 25 ranks. There is no way on the planet you could call that a 'thin line'. So something is missing from Polybius' account.

If one takes Polybius' speira as a century, then halving its width whilst doubling its depth gives you a unit 4 times deeper than wide. 16 legions side by side would have a frontage of 1,600 yards. The Gauls and Spanish facing them would be at least 12 men deep, still not a thin line by any definition.

Polybius' description of the Carthaginian deployment implies that everyone was side by side in a single line: first the Spanish and Gallic cavalry by the river, then half the Libyans, then the Gallic and Spanish foot, then the other half of the Libyans and finally the Numidian cavalry. Livy however states there were two lines:

At length after long and repeated efforts the Romans closed up their ranks, echeloned their front, and by the sheer weight of their deep column bore down the wedge (cuneum) of the enemy which was stationed in front of Hannibal's line (aciem), and was too thin and weak to resist the pressure.

Notice that 'aciem' is in the singular; the wedge (Latin equivalent of crescent) is in front of a single, continuous line which means there are two lines.

How does one reconcile these two passages? Here's a reconstruction that takes everything into account. Presuming the Roman infantry deployed on a frontage of 1,600 yards (more plausible as seen below), each legion would have been about 50 yards deep (16 + 16 + 10 + space between the lines) and 100 yards wide.

Livy makes it fairly clear that the Libyans on the flank are fronting the Roman foot, not the cavalry, as only the Gallic and Spanish cavalry engage the Roman right flank cavalry. That being the case, the entire Carthaginian infantry line is about 1,600 yards wide. The Libyans number 8,000 men and The Spanish/Gauls about 20,000 at least.

Livy implies that the Libyans, like the Gallic/Spanish centre, were in two lines:

As the Romans rushed on incautiously between them, they were enfiladed by the two wings, which extended and closed round them in the rear. - Livy: 22.47

Notice the 'extended' (mox cornua extendendo clausere et ab tergo hostis) The Libyans on each wing extend their lines and then wrap around the roman rear (tergum). This manoeuvre will be repeated later by the Romans at Cynoscephalae. where an enterprising Tribune detaches the principes and triarii lines to wrap around the rear of the unrouted phalanx. It is however impossible to extend a line that is engaging the enemy, which implies a portion of the Libyans fought the Romans frontally whilst the rest moved around and attacked them from the rear. This corresponds to Polybius:

Thus it came about, as Hannibal had planned, that the Romans were caught between two hostile lines of Libyans—thanks to their impetuous pursuit of the Celts. - Polybius: 3.115

Each Libyan line would need to be a decent depth, say 10-deep. That means that each Libyan wing was 200 yards wide (4,000 men / 2 lines / 10 ranks). So the Libyans took up about 400 yards of frontage. That leaves 1,200 yards for the Gauls and Spanish.

If the Spanish are 4,000 strong and the Gauls 16,000, they deploy in two lines, one right behind the other to give the appearance of a single line - Hannibal wasn't showing any of his cards before the game began (the first line advances as a crescent only after the battle has begun). The first line consists of an equal mix of Spanish and Gallic units organised in alternating speira. It has 4,000 Spanish and 4,000 Gauls and is 6-7 men deep (8,000 / 1,200). That is a thin line. The remaining Gauls - 12,000 strong - form a second line 10 deep, a standard depth.

These figures are somewhat flexible but the general pattern is clear - two lines take into account the 50/50 mix of Spanish and Celts in the crescent, account for the thinness of the crecent and explain the existence of a second aciem behind it. It also explains how Hannibal would ensure the Spanish - who had planned to defect (Livy: 22.40) - would have no choice but to fight. With Gauls on either side and behind them their only way was forwards.

Assuming the Roman horse deploy 6 deep at 2 yards per cavalry file, the left flank Allied cavalry will have a frontage of 1,600 yards whilst the Roman cavalry on the right flank will have a frontage of about 530 yards. This last number is the distance between the infantry and the river. Hannibal's Numidians match the frontage of the Allied cavalry at about the same depth, however his Gallic and Spanish Cavalry must deploy nearly 20 deep to match the Roman cavalry.

Rereading Livy's account of the cavalry fight (thanks Richard), it's clear there was no need for a wrap around. The two bodies of cavalry, initially deployed a standard 2 yards per file, compacted up as rearward horsemen advanced between the files of the horsemen in front to engage the enemy, then dismounted to fight on foot. Once the cavalry fight had become an infantry fight the Romans were at an irremediable disadvantage. On foot they occupied about 1 yard per man which gave their line an average depth of 3 men. The Carthaginians however had a depth of about 8-9 men. They could now use their numbers to drive the Romans back.

Let me tackle the course of the battle in another post.



*With no maniple-wide gaps between, but that's another topic.

[RichT]

This all sounds very familiar - have you presented this theory before?

It's all well and good, but I will repeat (or say for the first time) what I said last time (if there was a last time) - these sorts of numerical calculations are deceptive because there are too many imponderables (eg just taking the Romans, width of file, depth, size of gaps, not to mention number of Romans).

As for your unusual interpretation of Livy to mean there were two Carthaginian lines - it does way too match damage to what Livy actually says (and remember Livy is basically paraphrasing Polybius).

On a philosophical note, there are two ways of dealing with ancient battle accounts - one is to try to understand what they say, explaining the units present and their movements so far as possible from the account, and go no further; and the other is to construct a narrative or model of what might have happened and fit the ancient accounts around it. I'm deeply suspicious of the latter, which seem always to be built on exceptionally shaky ground and which too often involve doing violence to the ancient accounts in order to fit them to the model.

[Chuck the Grey]

Some thoughts,

What was Hannibal thinking?
I believe that the crescent formation was designed to buy time at the cost of distance. Battles often revolve around a time and distance problem; will my units be able to cover the distance in time to help win the battle (think Wellington and Napoleon watching the Prussians march to contact at Waterloo).

Hannibal was aware that his infantry couldn't hold off the Roman legions forever since in two previous battles the Roman infantry had be able to break through his infantry line late in the battle. The crescent formation was to buy additional time while giving ground to the Roman legions. This would give Hannibal's cavalry more time to defeat the Roman horse, drive them from the battlefield, rally, and attack the Roman infantry.

This of course would only work if the Iberian and Gallic units were able to maintain discipline and cohesiveness long enough for the Punic cavalry to be successful. This boils down to two factors; trust and confidence in Hannibal, and the nature of fighting withdrawal.

The Gauls and the Iberians trusted Hannibal and had confidence in his leadership. Under his command they had already defeated two Roman armies in battle and they had no reason to doubt that this battle would also be a victory. When the Gauls and Iberians  were told that they were to delay a Roman breakthrough long enough for victory, they trusted Hannibal and his plan. The was reinforced when Hannibal took his position in the center of their line (apparently) placing himself at risk if the Romans broke through.

A fighting withdrawal slows the enemy advance (costing time) by giving ground (costing distance). It is not meant to stop the enemy's advance, but to slow the enemy down. This reduces the intensity of combat at the front and preserves the fighting efficiency of your soldiers. The crescent formation helps this since as the Romans push the leading units back, they encounter fresh units that again slow the advance down until the fresh units are also pushed back. And so on, and so on, etc., buying more and more time.

What were the Romans Thinking?
The Romans knew, like Hannibal, that their legions would be able to break through the Punic infantry eventually. The Romans also were aware that their cavalry was of lesser quality than Hannibal's and would not be able to stop the Punic horse for an indefinite period of time.

The Roman plan was to mass their legion and smash through the Carthaginian battle line before Hannibal's cavalry could win the battle. Simple and straightforward.


Reality Sets In
I'm sure the legions in the center of the Roman line thought they were winning the battle and their plan was working. The Punic crescent was stretched to the breaking point and they were probably achieving small local victories. Then Hannibal's Libyan veterans closed in from flanks and Hasdrubal's heavy cavalry attacked the rear of the Roman legions.

The Romans had lost the battle for time.

[Justin Swanton]

Let me cover the battle this evening. Working through Livy's Latin I came across a classic case of the standard translation not translating the Latin but rather inventing what the translator thinks Livy should have said. Livy in fact mentions a second Carthaginian line behind the front crescent more than once. Stay tuned...

[RichT]

Let me guess - 'in mediam primum aciem'

Maybe something abut the bow at Cannae would be more worthwhile - Romans and Carthaginians were both hot on slings and javelins but seem a bit behind with bows - how come? Or were they archery users and I'm just ignorant of it?

[Duncan Head]

There are quite a few scattered references to Carthaginian archery, but apart from Appian's "Moorish and Balearic archers and slingers" not many specific mentions of its use in battle. 

[aligern]

Do I recall Caesar hiring Numidian archers?

[aligern]

Just three points,
1) Hannibal was upon an elevated position at the village of Cannae, it gives a good view of the plain. The Roman commanders  do not gave the same view, they are positioned on the flood plain of a river. Hannibal can indeed be flexible in his response.
2) The Roman army will have taken a long time to deploy. Their layout is unusual and that always causes problems. It is not a deployment that is easy from marching out of camp(s) . Thus they will have displayed their formation to Hannibal long before it was completed, giving him time to react to it.
3) Falling back fighting is something that barbarians do as well as 'disciplined' troops. For example the Helvetii and Ariovistus Germans against Caesar. I venture to suggest that  the nature of short intense fights followed by mutual pull backs to rest leads itself to that sort of rearward movement if one of the protagonists keeps pushing forward. Roman rank replacement within their formations might well play a part here. The legionaries at Cannae would see no trap, their enemy was falling back, they were following up, a few rounds of this and they would  be through.

Hannibal's genius was the management of time, but not by ordering his trained barbarians to fall back or do anything that might lead to confusion or a panic.  He set them up so that the natural processes of conflict would lead to the Romans being crowded in the centre and  with exposed flanks . It does not matter too much whether Hannibal formed his Gauls and Iberians deep but in one front line, or had two libes one in back of the first. The key  is that the Romans had to get through the centre and either a deeper formation or a reserve in the centre would achieve that.
It also seems logical that with the Carthaginians presenting a concave front, the Roman legions in the centre would contact first, but those on their flanks would not be fighting yet because they would try and hold the as a line rather than break ranks by advancing beyond the first line of  contact. Contact in their hipugely deep formation tgey would wait for the Carthaginian line to retire and firm a straight front before engaging.
Roy

[RichT]

Is it just that the bow is not part (a major part of) of the WMWW then? (Dives for cover).

Which does suggest (if we didn't already think it) that there's not much to choose in terms of battlefield performance between slings, bows and javelins and people just use whatever their culture is used to using.

Fighting withdrawal at Cannae - if you forget for a moment everything you know about Cannae and about what 'must have happened', and just read Polybius (quoted above) and Livy, I don't think you would ever conclude that the Celts conducted a fighting withdrawal.

Incidentally I was right, I do remember this:
http://soa.org.uk/sm/index.php?topic=4062.msg52651#msg52651

Those who do not learn from history are condemned to repeat it.