GreivousKhan said
General rule of thumb in a pre-industrial age is 0.5% of the general population, 10% is impressive even in a modern society. There are many, many different estimates about the sizes of the army and the population in the Roman Empire; one of the most commonly quoted interpretations place them at 350,000 combatants among a population of 50 million by the end of Augustus's reign, or in other words the fighting components of the army made up about 0.7% of the population at a time when the core of the Roman empire was at peace while the frontiers (particularly Germany, Syria, Mesopotamia, and Numidia) were in a state of near-constant warfare. That's just a basic estimate from a highly militant and organized state.In any case I don't really care too much this being a fantasy setting and all, but that number did make me do a double take. (and I got the estimates closer to 6% rather then 10)
Not necessarily. There's no single average or even a consistent rule across the ancient and medieval societies. Especially if Rome enters the equation.
Rome isn't a good comparison to make when discussing feudal societies or nations built on the premise of Holy Orders where their soul purpose is militant in some fashion. In the case of Rome, they were similar to Greece in the way they built their armies. It was more common for the Roman aristocracy to field predominately nobles and aristocrats into their armies. There weren't very many commoners or peasants in their armies, and if there were those filled levee rolls and probably weren't counted, since they're plebians and not master-race Latin land-owners.
The Romans - fielding their nobility - in essence could only have a smaller army than usual. On top of this, Rome rewarded their men for partaking in campaigns with personal land for them. And their smaller army meant they got arm and equip them better than the Germans and the Gauls.
The Germans and the Gauls on the other hand were considerably less centralized than the Romans and more tribal. They weren't as rich as the Romans, but their society's structure meant that they often employed more people in an army on a whim since men were the designated fighters. Women and children were the farmers at home and rarely - if ever - went to the field. There was no distinction in class in sending them out to fight, so long as they had something to kill with.
Europe in the Middle Ages kept up the same pattern, though a lot more hap-hazard. Knights would have been the "standing" force of medieval armies and continued the practice of the nobility being in the field. However they were not the biggest or even the most populous fraction of their army. Peasant levees were greatly employed across Europe for brief campaigns: more often during winter when there was no work to do otherwise. There was minimal cost associated with them as well, since they were often pulled from their homes and ordered to kill with whatever they had, or were minimally armed and trained with the basic essentials (perhaps some minor drills that last a couple days, then they force a spear in your hand and send you off to be the front-line between the nobles and the enemy).
When the conflict was over or the farming season began these men would return home to their normal duties with minimal or no reward. If they wanted to come off richer than their best bet was to simply loot.
In the far-east the pattern was very different, and it was very early on the Chinese learned to deploy and construct massive armies. The Warring States period marks a period in Chinese development where the Chinese people began to field truly excessive armies. This in turn lead to reforms in the administration at home and marked a shift from Feudalism into later or intermediary stage feudalism between the Old Nobles and strong centralized bureaucrats. Large-scale infrastructural construction at home helped to ease the burden of the logistical effort, such as the construction of the Zhengguo Canal in the State of Qin. The reforms to infrastructure, government, mathematics, and shifting military doctrine brought rise to each of the Warring States to command and deploy immense armies of up to a million.
Between them the Nomadic Turkic peoples may have looser demands on who goes to war since every man irregardless of role or condition was seen fit for war and the entire tribe could be mobilized in defensive or offensive maneuvers, hence "hordes". Their life-style already depended on moving around and hunting so every son was trained to ride and use a bow in the same way many boys were trained to use a bow in medieval Europe. But the Turkic Cumans needed to hunt and they more often used their skills to get their daily bread, instead of chasing of the occasional wolf.
Constant restraints in military size comes with a more complex society that requires more people performing more specialized jobs. During the Industrial era this meant more people filled in factory jobs as opposed to becoming some 13th century duke's army. Inversely, as we move ahead there may not be so much of a need to human abilities in working as factories become more robotic and low-input high-output computing becomes the norm in not only manufacturing but other fields of work, and it might be argued society then might come around again to an era where we can economically field large levee armies again.
And arms grow more often in war time than they do peace-time. So though the USSR and the US kept large armies, it wasn't a full-blown hot war which would have accelerated the demand to recruit more soldiers and expand the national armies to the 10% point and to effect the working demographic at home (more women might take the place of men if they all go to war, as they might on Lancer's island).
Their are other factors as well, such as a cheap source of food to feed larger populations of men; which might be dependent on one's power in trade or the fertility of the island which correlates to the habitability of the land. Political factors might be included as well, such as in the case of Rome where the Proconsuls could carry out campaigns independent of Rome itself, further skewing where the army might be concentrated. Or even how the sizes might be reported in the long-term. After all: who really cares about peasants?
On the peasant note again, the Grand Prince of Moscow Dmitry Donskoy employed and used an army ranging from 70,000-120,000 men against the Tatars, most of which were probably the peasantry.
