Medievalish kingdoms and empires. How big is too big?

So I'm putting together a story. Lots of big ass kingdoms with ye olde dark ages technology and castles and so on and so forth. With a bit of magic on the side.

The problem is, how big is too big for these things?

Could you sustain an army of a million or would it just collapse in on itself because it's a logistics nightmare?

How many people could you fit in a medieval city before everyone just starved to death or something?

What's a good scale for these kinds of things? Any help is really appreciated.

Oh really when?

Short answer: It depends on a lot of factors. It can be a lot more than you'd expect, but not very often...conditions need to be perfect for that.

Long answer: Rome broke the 1 million barrier some time around 0 CE and held on to populations near that level for as long as the western empire lasted, but collapsed back into small-town status very quickly after that (the Gothic War apparently reduced the population to around 30k...). It all depended on having the infrastructure in place to support a city of that size. Food, raw materials and so on not only had to be produced but also delivered to the city, which required a working, well-maintained road network. The city had to have a good source of fresh water, or disease would inevitably act as a cap to the population. Rivers wouldn't work forever as eventually the city would start polluting them to dangerous levels. The romans built their aqueducts as a workaround (because by all accounts, the Tiber was downright vile during the golden age of the empire, and the groundwater reserves were stagnant and boggy), and the few similarly-sized conurbations had similar systems in place.

But more than that, people also had to have a reason to live in the cities. Two factors encouraged this. First, hard times out in the countryside would invariably force people to move to the cities and/or starve. This could provide a temporary boost to a city's size, but that was rarely sustainable in the long term. Second, a city could become prosperous enough to keep and even attract a large population even while everything's going fine outside. That usually meant trade, and lots of it. A major trade hub would be so wealthy people would migrate there without any pressing need, swelling its size dramatically (sometimes causing its socio-economic collapse in the process...).

In addition, a potential medieval metropolis requires a very good location. Rome was a bit of a mixed bag in that respect. It had very good ground (on the hills) but also extremely bad areas (large tracts of land between the hills were essentially disease-infested swamp). Imperial Rome was able to get the nastier areas under control by employing the huge amounts of labor they had available in public-works projects to drain and build over the swamps, but that was a multi-century effort. Other very large cities all tend to be built around some kind of high ground, both for reasons of security and for health (avoiding stagnant pools of water).

The location must also be defensible. Rome was gutted by the Gothic War because while it was still very, very rich it was no longer able to effectively defend itself, got raided repeatedly and eventually pillaged into insignificance. That needed a combination of natural defenses (again, high ground), a large and well-prepared military...and a sufficiently large controlled area around the city to provide a buffer and early warning so that said military could be raised and prepared. Fortifications could keep cities safe until relief forces arrived from elsewhere, but they also acted as barriers to expansion and constraints on city size, and those cities that relied heavily on them never grew to the humongous sizes of Rome or its peers.

Simply put, a medieval megacity would be possible through a rare combination of natural, technological and socio-economic factors, but only very few places on any given planet would have that.

For the most part, cities recognized as impossibly huge metropolises at the time maxed out somewhere in the 250k range, and breaking the six-digit barrier was fairly unusual all by itself.

I found this handy list on The Other Wiki to give an overview of historical city sizes, but be aware that many of those numbers are under significant debate due to lack of reliable sources (many early historians -and quite a few more modern ones- were, shall we say, prone to slight exaggeration ).

edited 3rd Jun '14 2:06:50 AM by MattStriker

Reality is for those who lack imagination.

It is estimated that the classical Roman Empire had a peak army size of almost half a million. And medieval China may have had as many as 2 million soldiers at times.

Of course, if some sort of fast magical communication is available, then commanding a large army is easy, and getting it adequate food and water becomes the bottleneck.

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If you're using a lot of cavalry, feeding your horses becomes another major logistical problem. People like to think "oh, horses are self-fuelling, just put them in a meadow somewhere for a bit"...not true. You want to keep major cavalry units moving, you'd better have a very good logistics train to back you up. Look up Napoleon's Big Blunder (the russian war)...one thing the french completely dropped the ball on was supplying their cavalry, and that probably caused them as much trouble as the harsh winter.

Basically, an army has a pretty damn huge logistical footprint. Every fighting man needs the work of numerous civilians to keep them in the field, and the bigger an army gets (reducing its ability to live off the land in a pinch) the worse it gets.

Reality is for those who lack imagination.

Let's not forget that most horses can't do well on grass alone, especially if they're being worked as hard as war horses.

Historically, it's difficult to determine because a lot of evidence suggests no such thing exists unless you say "everything".

Civilizations historically have covered entire continents for example the Huns held an area almost the size of present-day Russia with horseback and arrows. The Romans had all of Southern Europe and much of the West and North. Yet it wasn't the size of the territory that did them in ultimately. (Rome's biggest problems were it was complacent in battlefield tactics and technologies and politically poorly led in the later stages of the Empire. The Huns never could ultimately keep together and fractured internally.)

Population wise is widely dependent on the food production status and certain technologies. The Aztecs and Maya had populations exceeding millions at the time of the Spaniards first arriving. They had advanced irrigation techniques and widespread agriculture and thus could support such a population. (They were done in by a combination of plague brought in by Spaniards of which the Mesoamerican cultures had no defense and vastly superior battlefield technology and tactics such as cannon and horse cavalry.)

At medieval technology levels agriculture and typical distribution methods of the era could conceivably support populations on the order of over one hundred million and empires the size of continents.

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you going for medieval technology ? or medieval social system ?

ancient china and ancient rome had a lot larger armies than medieval europe. if you going medieval europe style with lords, knight and castle : tens of thousand is probably maximum. agincourt and crecy is under 50.000 and have kings in them. battle in english heptarchy is only thousands maximum. minor battle, such as between baron and knight, could be as low as hundreds. the more troops you want participate, the less medieval it is, its going become powerful kings/emperor of centralized strong states against each other.

Here are some things to keep in mind:

1) Nationalism. A kingdom, and empire, and a country are three very different things. Kingdoms aren't terribly stable. The medieval feudal system was basically a hierarchy of loyalties, and when loyalties changed or there was a dispute for the crown things came apart fast. Empires tend to rise and fall- you can have a very large empire for a single generating while the man who conquered it is around to keep everything together, only to have it fall apart when he dies. Countries are more stable because the population identifies as being a citizen of that country, rather than as a subject of a particular noble who might be whatever king's side in the next war, or a member of a tribe that has some external state ruling over them. The government may change, but the country itself less likely to break apart. Bottom line: social structure matters a ton.

2) Disease. A huge problem with packing lots of people in one place. Having magic that can reduce the chances of plague outbreak would be really helpful.

you might also take a look at geography. With medieval know-how and motive, you really don't want to absorb those fields and mountains. You merely want to reach out to the next city and tax them. If it is not worth the money and manpower to cross the sea or climb the mountain, you don't. it then becomes the den of la Resistance.

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