So first of all, I assume this is what happened, or at least that it works this way if there was some other cause in our particular case:
2 Realms at war, one sitting in a rogue region, the other enters & stirs up peasants, preventing a battle because both sides hate rogue.
I imagine "murderous" or some other workarounds exist, but would it be easy to simply run the Diplomacy check before stirring up peasants and if a battle would otherwise occur, suppress the peasants.
Secondary would be the same for monsters, but that doesn't occur so often as to be much of an issue