I can only see this kind of working if it was some sort of reverse rebellion, where the king initiates a rebellion against a target, granting him and his supporters a chance to defend themselves as their regions are taken away from them.
And while this sounds like it would be cool, I think it would also be a lot of work to code.
I also always think it a poor idea to assume people will react to unjust actions. Many are bond to never care, and others are bond to not want risking being seen taking a position.
