I *think* it's just that the campaign map is divided into a (very large) number of squares, and whichever square the units are in when they meet is where the battle takes place. I'm assuming that every map has been pre-generated in loving detail - with a lot of effort!

My question is what they do about increasing the size of settlements (assuming they do) or adding forts if armies build them (I assume the battles take place around the forts).

I guess the only annoying feature about the campaign map is that the rivers are always very angular - but the battle maps more than make up for this with their beautiful meandering :)

Quick question, if I may... In the first battle in the Prologue, it refers to a bridge a number of times. Is there actually a bridge there, or just a ford? If it's the former, I really need a new graphics card!