Hi TheCrusader

Yes, we can capture both capital and historic cities, but they cannot be renamed.
As you can always expect, there is definite resistance! The capital city will most likely have a lot more resistance, and you can see the "Force" in the valley menu for each capital... I expect this to be the attack power/amount of troops in that given capital, but don't quote me on this!

As far as I know, it doesn't cost a mercenary camp point for a city. But the historical cities do give you additional population/glory points depending on their icons.

Approximately, how much troops we need to capture some historic city?