Having played the game several times with a group of friends I have found an issue come up repeatedly in almost every game. The issue being someone initiating an attack on someone then during the calculating combat strength phase they realize the person they're attacking has more strength then they first assumed (due to support they didn't see or just adding wrong in their head) they decide that the battle will be closer then they originally thought and withdraw their attack.
My question, something that I can't find in the rules is that are players allowed to initiate an attack on someone then decide to withdraw the attack after seeing something they didn't realize at first or must they go through with the attack anyways even if they have no chance of winning? When is the point of no return of march orders?