How did ancient Gaul raise armies numbering in the tens and hundreds of thousands?

[u/Capital_Tailor_7348]

According to wikepedia modern historians estimate that at the battle of Battle of Alesia the Gauls had a combined number of as low as 70k and possible as high as 180k men. Meanwhile during the Middle Ages during the battle of Agincourt the French had at most 25k soidlers and that's including armed servants. How the hell did a tribal society like ancient Gaul raise more troops then France during the high Middle Ages?

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[u/Libertat]

Regarding the specific of late Gaulish armies and numbers, and in relations to the post /u/dandan_noodles linked or this previous answer, I would point out that the various numbers were have at disposal for the Gallic Wars aren't necessarily arbitrary but have to be held in scrutiny and contextualized to understand their meaning.

A first obvious issue is that the numbers given for the battle were nuanced by ancient authors themselves, including Caesar. When it comes to the besieged forces, Caesar accounts for 80k while Plutarch mentions 170k. For the relief army, Caesar mentions for 257k men while immediately removing 8k that Bellovaci did not sent out of their 10k contribution, which should give 249k but somehow becomes 248k, which is rounded up by Florus as 250k, Polyaenus as 200k while Plutarch gives 300k men for the relief army alone (A. Deyber proposes that Plutarch confused numbers and that the aforementioned 170k should be for the whole Gaulish army).

Where does all these numbers come from? They were collected by witnesses or actors of the event (especially Caesar that, while not necessarily making up things, was certainly giving numbers to his convenience), but also authors that depended from Caesar or other witnesses, archives or historians (as Valleius Paterculus, who gave an overall much lower estimate of losses in Gaul), but are obviously contradicting and seem implausibly (for logistical reasons) high.

It would be tempting, reasonable even, to argue they just gave an arbitrary number either for propaganda or narrative's sake, or because they had to rely on sources that frankly didn't gave much interest or had direct connection to the enemy side; meaning that these number are essentially dressing "there was so many of them". But while all of this is plausible on its own, it's also a fairly convenient post-facto explanation : after all, while there is still issues estimating military or civilian losses in contemporary or ongoing conflicts, numbers proposed are not just random proposals, but more or less relevant ballparks for the targeted audience, in the case of Caesar, namely the Senate and the Roman people he wanted to gain support and later to provide justifications and promotion of his actions.

A question we should ask ourselves would be : why Caesar, and following authors, went with this implausible number?

Gaulish armies were not mobilised by the petty-states themselves but by the warring aristocrats, who could themselves raised their personal troops alongside or instead of a broader mobilisation (Orgoterix, Ambiorix or Vercingetorix leading a "smaller" corps of 10k to 15k men) : in addition to client/vassalic armies, still these larger mobilisation seems (on the basis of coalitions where each people was supposed to bring a given number) to have been made on the basis of the people, from which a theoretical military force was supposed to be extracted, likely on the basis of specially made censes as Caesar accounts for the Helvetii.

So, part of the numbers mentioned by ancient authors could have been made on the basis of theoretical capacities of various peoples built on fiscal or military censes, capacities of various aristocrats, etc. and formalized at least during the war councils that preluded the actual military operations in deciding the broader strategy but were also a mean to boast about military strength and thus calling for regional primacy in assemblies and leadership. These theoretical mobilisation numbers are obviously not met numbers, regardless of the time and place, but even more so in a context where the various Gaulish petty-states lacked the kind of structural authority to fully enforce them even if they wished to. Eventually, a good part of mobilisable men, especially the least skilled "rabble" that wouldn't have weighed much militarily or even be a logistical hindrance, might simply not have been mobilised at all or, if so, remained as some sort of homeguard.

Hence Bellovaci in 57 BCE boasting being able to gather 100k men, from which they promised 60k as their best (DBG, II, 4,5; or the same people in 52 BCE having to raise and send 10k to Alesia and managing to do so with 2k only.

We could as well point to the fact that, as warring aristocrats were seemingly responsible of the mobilisation, that several of these joined with Caesar as the Arvern Epasnactos did at Alesia, or that several of them might have hesitated or not joined with Vercingetorix even if their people did, to further propose a possible discrepancy between theoretical and realized mobilisation.

Even initially met thresholds aren't the same as how many people are actually present in the field : these have to move from their mobilisation point to the operations (either pre-determined or moving) and have to go trough skirmishes, laggards, desertions, miscommunications, delays of all kinds especially if coming from a distance place : several people that partook in Vercingetorix' coalition were distant from several hundreds of kilometres away from Alesia, with the war assembly having convened in June-August and the siege beginning in late August and the relief army coming in September. If anything, it's a testimony to Gauls' military capacities and road networks they were able to gather an impressive relief army so quickly for the siege.

These numbers were no state secret, openly discussed and advanced in assemblies and, according Caesar, written down in the case of Helvetii (DBG, I, 29). In addition to contemporary actors or witnesses eyeballing or guesstimating forces, at least some could have been involved in giving away some of these, interrogated, allies, prisoners, etc.

When ancient authors mentions 250k men in the relief army, and more amongst the besieges, it's is very likely for various reasons, logistics and the capacity of Gaulish commanders to even handle such numbers first-most, that they do not represent a serious estimation made on the field, either calculated or guesstimated : too many descriptions by Caesar on the width occupied by Gauls outside the fortifications are obvious exaggerations.

But it is possible that these numbers, outside obvious boasting and narrative licence, also gives us something about the perceived (by Gauls and/or Romans) military capacities of peoples or coalitions, possibly mixing present, participating (we know that a decent chunk of the relief army simply did not partook in battle), mobilized, theoretical numbers, etc. It doesn't make them more usable for having a clear view on actually present and fighting numbers, although estimates on archaeological, literary and logistical concerns is not only possible but proposed, but isn't useless or an ancient way to say "a gigabillion" either : for the Siege of Alesia, it'd also be a measure for its strategical and tactical importance, with a largely insurgent Gaul, which accounted for possibly 10M inhabitants, with a corresponding military efforts from the peoples that decided to throw their lot against Caesar.

[u/gmanflnj → u/Libertat]

Can you clarify something. I understand why medieval armies were much smaller than Roman one’s because of way larger state capacity on the Roman’s part, but the Gauls, afaik, had fragmented societies ruled by nobles and limited infrastructure just like many of the medieval kingdoms, how were they able to mobalize such large percentages of their population as soldiers, afaik, far in excess of most medieval societies.

[u/Libertat → u/gmanflnj]

As we have no surviving censes of either independent or Roman Gaul, estimating the population for the whole region is essentially speculating on later estimates, archaeological evidence and some vague mentions : hence the vague fork of 10 to 12 millions which is broadly agreed on. It is even more risky to do so for individual peoples as in spite of urbanization (with some rare sites maybe having up to 10k inhabitants) the large majority of the population (and of mobilised troops) lived on the countryside. That and the disparity of size and power of Gaulish peoples would make such a population-per-people difficult at best : I don't think anyone seriously tried to propose one since Fernand Braudel did so by proposing Arverns were made up of one million people.

At this point, you'd see why trying to discern the proportion of mobilisable, mobilised and raised military force would be a perilous exercise at best, numerology at worst. If we try still for the sake of illustration, we'd have something around 3 to 4% of the population (conveniently forgetting about people not joining up or results of years of war). Which, giving, the state of general and organised insurgency, isn't that high and could fairly be comparable to what Romans had been able to field during the Punic Wars.

Now, you also made a very reasonable point about not just the numbers, but Gaulish societies were even able to muster important armies to begin with. We are unfortunately in the dark about the specifics, which probably varied from people to people, and what informations we have are taken straight from De Bello Gallico, which are superficially interested on that to begin with and writes about a situation in the very late period.

Although probably backed and prepared by a more or less important state structure, notably with Aeduns who had a commander-in-chief and general officers appointed by the chief magistrate and the "senate", it was likely still the responsibility of the warrior-aristocrats that made up the nobility and the "senates" of various peoples. While some aristocrats could quickly raise some hundred or even thousands for the most powerful among their own clients, there weren't any readily mobilisable troops in Gaul, let alone standing armies : completing numbers would require to call for a larger mobilisation amongst the population as in Antiquity, and ancient Gaul was no exception, [warfare wasn't vocational but a public matter that formally concerned all freemen although it's impossible to know how many were actually armed with at least a spear, which is an important difference with the lack of general levy in medieval warfare. (u/Rittermeister).

Caesar mentions that messengers were sent to proclaim or make proclaimed the state of war in each pagus. The term is Latin and generally have the sense of district or territorial subdivision, some firmly subordinated to the people as those of Aedui or Arverni, some fairly autonomous or even independents, as for Helvetii or Morini, with a pagus being determined in all likeness by different markers as were civitates, namely sanctuaries, oppida, open agglomerations, etc. In the earlier centuries, it's possible that pagi were the more important focal point, with civitaes being a "federation of pagi" of sorts, with an assembly-in-arms playing a major role, but at least for the more centralized petty-states of Central Gaul, these would have been much more of a formality except in maybe transmitting and organizing down the mobilisation trough smaller scale grouping as tribes or households.

This shouldn't be taken, however, as a sign of centralized armies : both in mobilisation and commanding, the rule seems to have been of a cohabitation between a war council (either on a regional military coalition or a petty-state) and poorly hierarchized warchiefs each with their own responsibilities and troops, although the existence of boars and spear standards seems to imply at least some scale difference between units. You could argue pointedly that this difficult "horizontality" and the size of armies made the joint effort at Alesia more uneasy than not : some leaders, as Ambiorix or Commios, rather elected to focus on smaller numbers.

We don't know of the criteria for mobilisation (age, health, wealth, exceptions, etc.), but giving warfare was a civic and religious precept, I'd take liberty to say it might have concerned a lot of people still, especially as access to warfare and civic life seems to have somewhat democratized in the late period, along the constitution of urban and peri-urban clienteles, even if some people practised a "bipartition" of mobilised forces as Bellovaci or those part of Ariovist' coalition in forming sort of a territorial reserve army.

Apart from that, and that coalitions that gathered multiple people with their own headquarters and war councils functioned similarly by sending messengers and requesting hostage exchanges between peoples, we don't have much left to the question. As much as we don't know, I might partially answer your concern with pointing Gauls were likely more numerous than traditionally held and able to mobilise ten of thousands (without any kind of certainty about the numbers actually present on the field), and had enough state and institutional structures to undergo mobilisation amongst the population.

EDIT : It's worth remembering that the Siege Alesia is an exceptional event in the history of Gaul, to the point it might legitimately be considered the biggest battle fought in France before the Catalaunian Plains at the earliest. While large battle born out of board military coalitions are attested before, as with the Battle on the Isère River or the Battle on the Sabis River, the efforts made in 52 BCE seems to have happened on a much bigger scope, involved much more people, and with a more purposeful strategy by Vercingetorix. While there's definitely something to be learned about Gaulish military capacities from it, it shouldn’t be taken as wholly representative of Gaulish warfare either in make-up or mobilisation.

[u/dandan_noodles]

You might be interested in this post and the discussion beneath, which covers a lot of similar ground. In both cases, the vast bulk of the population were peasants, but in Iron Age Gaul, these peasants were called upon to fight in large numbers, while in medieval France, they primarily existed to support the knights and men-at-arms through the rents they paid.

I will note regarding this specific example that at this time, the king was effectively disabled, and the Dauphin was not able to effectively assert royal authority; France was thus embroiled in a civil war between two branches of the royal family [not counting the English]: that of the Duke of Orleans*, allied with the Dauphin, and that of the Duke of Burgundy. The Burgundians set too-high a price to join the campaign against the English, and thus did not contribute any forces to the battle; the Armagnacs in fact had to take measures to keep the Burgundians from marching on Paris during the campaign of 1415.

Zooming in further, there were several contingents that were en route when the battle was fought, but did not arrive in time. These included the companies of powerful lords, such as the dukes of Brittany, Anjou, and Brabant which had not yet joined the host as well as large infantry contingents drawn from the towns of northern France that had been left behind as the French took their most mobile forces in an end-run to try to cut off the English line of retreat.

*This faction is referred to as the Armagnac faction because the Duke of Orleans's father-in-law was the Count of Armagnac

[u/gmanflnj → u/dandan_noodles]

I get the state capacity part, that’s fairly clear but presumably the Iron Age Gauls didnt have elaborate infrastructure or massive state capacity like the Romans, but still managed incredibly high levels of mobalization, how did they manage this so much better than medieval polities? 

[u/dandan_noodles → u/gmanflnj]

For my part I have similar reservations regarding the top level answer there, which i touched on in a comment below.

I will caveat that it's easy to underrate the sophistication of the Gallic war machine; they did have a system of consensus building assemblies, magistrates, coined money, and censuses committed to writing, all of which are really useful for raising armies. Regarding the first specifically, the Gallic practice of submitting the decisions of their deliberative bodies [which Roman sources call senates] to the assembly of warriors for ratification probably made service as such more attractive; if you armed yourself and followed your local bigwig, you got a say in whether your people would be fighting a war.

In the Late Middle Ages, the French kings had to raise the taxes necessary to finance wars through the estates-general*. This body gave the peasantry no representation, the Third Estate's representatives being elected by the towns, which comprised only a small slice of the French population. This made it much less effective at getting buy-in from the vast majority of the population, even as it ensured control remained in the hands of the nobility and the church [largely controlled by the nobility].

Notionally, the king had the right to call his whole people to arms through the arriere-ban, but in practice, almost everyone bought exemption as intended, the standard rate being 2% of the value of their movable property. This may be the result of the Late Medieval economy being far more monetized than that of the Iron Age. In any case, the labor burdens lords demanded of medieval peasants was quite substantial [Frances and Joseph Gies estimate something like 50% of a peasant's labor ultimately went to their lord's profit], though I would have to ping /u/Libertat for more on noble-peasant relations in the Iron Age.

So on the one hand, the medieval peasantry are under heavy economic burdens, and on the other, they have no say in matters of war and peace; in this context, it's not hard to understand why they'd prefer to pay their 2% and get back to work. The French king was able to raise vast amounts of money at times, but he spent it on expensive troop types like men-at-arms and mercenary crossbowmen, and it's questionable whether he'd be able to find armed peasants to fill out a latter-day Gallic phalanx even if he wanted to.

*also through debasement of currency, sale of pardons, contrived confiscations of property, credit, and other measures

[u/Libertat → u/dandan_noodles]

In any case, the labor burdens lords demanded of medieval peasants was quite substantial [Frances and Joseph Gies estimate something like 50% of a peasant's labor ultimately went to their lord's profit], though I would have to ping /u/Libertat for more on noble-peasant relations in the Iron Age.

As usual, we don't have this much to rely upon when it come to late independent Gaul, even less so for earlier centuries, due to the lack of literary sources; although there is an impression of a gradient of statues between freemen, clients, dependents, etc. whose relations and expected services would be different.

The comparison with medieval manorialism wouldn't out of place, with both a tendency to the spatial growth of big farms (along with dependent buildings) and the varying importance of small-to-mid exploitations with a peak in La Tène D1 (150 to 70BCE) and a marked decline in La Tène D2 (70 to 30 BCE) which might imply a concentration of property or dependency on aristocratic elite, a relation that would have continued afterwards giving the spatial and social continuity of farming estates before and after the Roman conquest.

It's worth pointing out that while a priori set out of the warring and religious functions (but not spheres) in late independent Gaul, women had an important social and economical role still, notably by working the fields, herding, etc. out-door works which were more male-gendered activities for Greeks, Romans or western medieval Europeans, along with the necessary ubiquitous in-door craftmanship. This would be highlighted by their patrimonial and personal status mentioned by Caesar, noting that they had an eminent ownership of their dowry as well of a proportional interest of the increased conjugal patrimony. That would have "freed" production time for gendered activities as warfare, religion, civic duties, etc. although women seems still to have partook in some aspects, at least in the IInd century BCE, with Plutarch mentioning assemblies of women arbitrating disputes between Carthaginians and Gallic allies.

[u/gmanflnj → u/Libertat]

Cause, I guess what surprised me is how Gaul was able to sustain such incredibly high levels of mobalization, because, AFAIK, even assuming very wide margins of error, the % of the overall population that they could put under arms was *enormous* and did so with far less state capacity than the Romans. So I was curious how the medieval people who had as good technology/infrastructure, seemed to have so much less surplus to be able to field such a tiny % of their people as soldiers.