Army size vs Civilian Population

[Lu_Xun]

Hello, first time on the Forum.

I have a question that might be of interest to those who hadlve a mind to build and run a campaign (Tony Bath, style) in either an ancient, medieval, or fantasy setting.

How big were armies compared to the civilian population that produced them and supported them?

I would expect the ratio would vary by culture depending on how militaristic a people were, and region based on agriculture and wealth. There is probably no "clean" answer, ... but I'm wondering if a general rule of thumb, for game purposes, could be arrived at that would indicate how many troups can be raised and supported based on a city population.

Thank You

[Erpingham]

Welcome Zachary.  This question has come up before, particularly in relation to the Persian empire. At that point it caused a long debate, which took in fascinating digressions into the 19th and 20th centuries.  Hopefully, we can answer more concisely this time 

One basic is a rule of thumb about pre-modern societies.  The number of men of military age (16-60) is approximately 25% of the population (50% of the population being under 16, and half the adults being women, who were usually not called on to fight).  This isn't dead accurate (we don't know what dead accurate is) but it is useful. Not all eligible males will be combatants (for example, they might be religious types excused military duty).  The situation is complicated in heavily slave-dependent societies, as they may have a higher proportion of adult males but slaves were usually non-combatants.

Within that general rule of thumb, though, things could vary a great deal depending on social organisation.  It also depended on quality control. The system may be more interested in the number of well-equipped, well-motivated recruits than the absolute numbers.

Hopefully, folks will turn out some examples.  I probably can, with a bit effort.  But lets see where other folks get to first.

Add: Couldn't resist one of my favourites, dealing with militia numbers.

https://openjournals.ugent.be/hmgog/article/70531/galley/194768/view/

Here, we are dealing with some solid archive sources, yet loads of guesswork is still needed.  Note, also, the use of a demographic rule of thumb of one soldier per household, each household having four members.

[Imperial Dave]

welcome Zachary. I am not an expert on numbers but there are others on the forum who will give you some fairly erudite figures.

You could always go with a 10% figure as a starting point (50% of a population is male. 20% will be too young and 20% will be too old giving 10% as a very rough idea of reasonable age for military service)

I will await my finely crafted reply to be picked apart 

[dwkay57]

It is an interesting question that I've asked about and also carried out some research. Most answers are educated guesses and extrapolations back from later data. The guidance provided by the Imperial Editor and the Dreaded are reasonable starting points.

In Slingshot 331, Paul Stein provides some guidance on the likely sizes of field armies and population numbers for 13th Century Prussian tribes. And in another thread on this forum we discussed the likely numbers of fighting men for various Celtic British tribes.

Are you starting at a macro level (i.e. this is the size of the population so this is how big their army can be) or the micro level (if the army is this big then the population must be this size)?

[Erpingham]

While looking for ideas on this that weren't medieval (apologies, but that's what I read about most) I did spot Bret Deveraux covered the subject in a blog post just before Christmas.  This attempts to give an idea of the structure of certain Classical societies and does have a section on army strength. 

[Jim Webster]

It is a combination of how many men of an appropriate age you have, but also what else are they needed to do.
More modern societies you need a proportion of working age men actually working, as opposed to serving. It also depends how long you're going to keep them in the army. Because you can get away with more men serving if the army is only serving after you've got crops sown and come back in time for harvest.

[Jim Webster]

While looking for ideas on this that weren't medieval (apologies, but that's what I read about most) I did spot Bret Deveraux covered the subject in a blog post just before Christmas.  This attempts to give an idea of the structure of certain Classical societies and does have a section on army strength. 

Fascinating article, thanks

[Lu_Xun]

Are you starting at a macro level (i.e. this is the size of the population so this is how big their army can be) or the micro level (if the army is this big then the population must be this size)?

I suppose I could make good use out of either when starting a campaign. I hadn't really thought of it as starting from either number.

Thank you (and all the others) for your input. I see that I may have opened a can of worms and while my inner game designer wants a simple equation, I realize that in actual history there must have been HUGE variation.

I would for example expect that Sparta, who (at least in popular understanding) had required military service, would have a higher percentage of its population under arms. HOWEVER, I am not a Greek historian, so I wouldn't at all be surprised to learn that that perception is just that, a function of how they are remembered, and that the military class was more selective/eleat OR that Sparta wasn't all that different from lots of city states that had compulsory service as a requirement for living in a dangerous world.

[Keraunos]

Welcome.  I can't offer general observations on numbers of soldiers to civilians in ancient and medieval societies and am grateful for the comments and links already provided.  However, on Sparta in particular you have distinguish between the Spartiates - the dominant group - all of whose young men were brought up in a strict system and compulsorily grouped into military messes - and the rest of the society that they dominated.  Sparta was quite unusual in having a permanent military class.  The numbers of people in this class were never very large. They were resistant to the entry of outsiders into the group and found it hard to replace the losses they suffered in wars to retain their brief hegemony after the wars with Athens in the 5th Century BC.  Apart from the Spartiates there were a group of people living in surrounding, subordinate villages, the Periocoi, who would provide hoplites and other soldiers for the army when required, and a vast mass of subject helots who farmed the land and - at least up to the Persian Wars - provided a mass of lightly armed men (7 men to each hoplite) who backed up the Spartans in battle.  Given the economic need to maintain its dominance over this suppressed population of helots, the Spartans were often reluctant to see their main army go outside their territory for long periods, so often tried to get allies to do its work for it.  So, all in all, Sparta is an odd case.  An unusually high proportion of its 'ruling class' had to serve in the army, but this class was not a large proportion of the population and its need to maintain rule over its subjects meant that it could not easily use its military might!

[dwkay57]

It all depends upon how "realistic" you want to be in your campaign and how detailed the information is that you building up and going to use. As you are the Campaign Master, you can make up whatever rules you think are appropriate and apply them. So something based on Tony Bath's ideas could work just as well.

Some of Colin McEvedy's work in the Penguin Atlas of World Population History and the New Penguin Atlas of Ancient History might be of interest to you if you wanted to get a feel for potential macro-numbers.

[Erpingham]

I think one "macro"  element to be borne in mind is that there is a potential pool, created by big demographic factors, but perhaps more important are the things that modify this.  For example, what kind of war is it?  Is it a war of conquest or defence, for example.  Is it "small war", which basically involves small elite forces but largely doesn't involve the masses unless they get in the way?  To pick up Jim's point, do you have an underclass to keep the economy running, leaving citizens free to go off to war?  Slave societies gave you such a class, for example.  And slave societies enabled you to buck the demographic trends because you could import more adult labour.  Then there is the financial power available to hire premium military power in the form of mercenaries or subsidised allies. Final quirk (for now) is, how long since your last bloody war? Pre-industrial societies often had a slow growth rate.  Take out a large chunk of prime manpower and it will be some time before you recover your previous strength.  A very good reason not to commit all your resources to a single campaign.

[Jim Webster]

Thespia is an example of the dangers of loosing too many men. They lost 700 at Thermopylae and suffered heavily at Delium

[DBS]

For example, what kind of war is it?

In addition to Anthony's excellent list, there are also the questions of duration, season and distance.  Greek city states, before the Peloponnesian War, did not tend to travel far or for long.  Muster the army, march over to your neighbour, burn down their orchards and pillage their farms, and fight a pitched battle if they deigned to emerge from the city before toddling home.  On that model, you could pick a non-critical moment in your agricultural cycle, and take a good chunk of available manpower for a week or two of recreational unpleasantness.  Different matter, as the Romans discovered, when the Punic Wars forced them to commit forces at distance for long periods of time, rather than just trotting into Samnium for that recreational unpleasantness...

Also, the largest and most successful cities and states tended to grow with a disproportionate number of non-combatants, namely slaves and non-citizen foreigners.  (Sometimes the foreigners fought for you, but varied.)  Whilst recent studies suggest that the famous Athens census by Demetrius in the late 4th century has been misunderstood, even the revision suggests that adult native males numbered circa 30k, of which 21k were wealthy enough to count as full citizens, plus some 5k foreigners and perhaps a 3:1 ratio of slaves to all the adult freemen.  One suspects that smaller cities would have had fewer slaves and foreigners in proportion to native adult males, but may have had a lower proportion of the latter wealthy enough to count as effective citizens worth mobilising, depending on the local constitution.

[dwkay57]

Yes, trying to model civilisation is very complicated and even our modern day comprehensive models sometimes fail to allow for the impact of the Quantum Weather Butterfly (Note: some people believe this creature is mythical whilst a few others think it became extinct when it flew in a fridge and was eaten by the cat).

But if we are just trying to put some approximate macro-rules in place to enable our battles to have more of a scenario to them, then it should be possible. Sone of it will depend upon the battlefield rules being used and the level of abstraction.

Of course, a possible spin-off question and thread is whether rules and army lists encourage appropriate army sizes and structures.

[Ian61]

Of course, a possible spin-off question and thread is whether rules and army lists encourage appropriate army sizes and structures.

A good point and of course relevant. Two points I am sure have come up before but are worth re-mentioning -
1. Generals often avoided a battle if they thought they couldn't win so uneven battles not as common as you might otherwise expect.
2. Playing a no-win scenario is not much fun.

Also

Quantum Weather Butterfly (Note: some people believe this creature is mythical whilst a few others think it became extinct when it flew in a fridge and was eaten by the cat).

Its got a Latin name, Papilio Tempestae so it must be real.