At the Field of Fire, The Reach and Rock kings united their forces to form an army of 55,000, 5,000 of which were knights. Isn’t that a low number for those territories? The Reach can raise 100,000 men and is the heart of chivalry, and the Rock can raise 50k themselves, not to mention easily field gold for sellswords heavy horse. What’s the deal? Is it that they didn’t have enough time? Aegon was busy with Harren and Argilac and the Vale though. Is it because the Hightowers decided to sit out?

warsofasoiaf:

There’s no clear answer, but I think there’s a few things we can determine.

First, the times. Westeros before was awash in countless wars between the petty kings, likely at least one per generation, so the populations of each kingdom were lower. Less wars mean more people surviving, which in turn means a flourishing in population. So in the fifteen generations or so of Targaryen rule, Westeros has seen a population increase.

Second, the establishment of a massive capital city, King’s Landing. Cities saw rapid population growth, and the addition of such a large one would lead to a rise in population as activity bustled in that region.

And of course, there’s the elephant in the room, GRRM is notoriously bad with numbers.

Thanks for the question, Roddy.

SomethingLikeALawyer, Hand of the King

I’d add a couple other things:

1. In an era with Seven Kingdoms eternally at war, you’ve got to keep enough troops at your borders to guard against being attacked while you’re in the field (see the Dornish attacking the Stormlands while they’re under threat from the Ironborn and the Targs) so more of the forces of the various kingdoms are tied up in garrisons rather than available for field armies.

2. During the Dance, post-Conquest armies probably adapted to dragons by splitting up so that you don’t suffer a Field of Fire. Hence why the armies of the Dance were so much smaller than in other conflicts.