Fantasy author looking for tips on army sizes

[Hal9000]

Well army size depends on which of area of the world you are looking at, which time and which nation.

The romans had 50 legions plus auxilliary troops and a navy at one point => 600'000-700'000 Men under arms. Of course, not all of these would be in the same place but where spread out throughout the empire. Rome would usually field no more than 10 legions in a campaign.

Medieval Europeans did not field very large armies - 20,000 maximum - (they lacked food), this changed with the introduction of the potato. Of course there are also exceptions here. In the 14th century the Tartars (100'000) fought against Dimitrij Donskoj (70'000-120'000).

In India the armies were quite large both in Roman times and after (up to 800'000).

The Chinese however take the top spot for largest single Armies in history wich could number up to well over 200'000 in a single battle.


What you want to do is estimate how big of a population your areas could support. You then take a certain percentage of that population (depending on how warlike the state is) and make them into standing armies. If you need more have them be conscripts

Be aware that your nations might be able to feed more people per km² since they have access to modern high-yield crops (unless they crossbred their own all over again).