Thu Aug 21, 2014 4:15 am
This depends upon a couple of factors: if you obtain one breach will that level all the walls of the city? If so, red attack.
If the city has several levels of fortification; I typically do blue attack and either orange or red defense depending upon the presence of an enemy army.
The only penalties to a red offensive posture is if you move into the region while you are in attack mode. In that instance, if you lose the battle you retreat from the region.
If you are in the region of the city you are besieging, there is no down side to being red, unless the enemy is strong and sorties from the city.
So nothing written in stone, somewhat situationally dependent.