You cannot move your capital while either the old capital or the new capital are being attacked, or the site of battles or unrest. If you are running a TO in a capital, then the target realm cannot move their capital until the TO succeeds or is defeated. I think there's some unspecified waiting period (a few turns) after you regain control before you can move it. Or maybe it's just once you stop getting the appropriate messages in the region report.
Wait, couldn't Realms move their Capital during the Daimon Invasion even if there was 'unrest', but at a penalty?
