Attack rebels rebelling against a different duke with same liege

crusader-kings-2

There is a (peasant?) rebellion happening in a neighboring duchy, and I'd really like to help the duchess there because she's betrothed to my son. I tried raising a levy and simply moving my troops into the same county, but I didn't seem to get to attack the enemy. Do I need to formally declare war on them? Can I even declare war on them?

Best Answer

There are two types of "rebellion" wars

  • Vassals revolt for some reason
    They may have refused a revocation or imprisonment demand from their liege, or they are a member of a faction that demanded something from their liege. These are normal wars, and you have to be called in as an ally. You may be able to request to join their war as well.
  • Peasant/Religious/Liberation revolt
    These are governed not by character interaction, but by the revolt risk of a county, which is modified by events, differing culture, and differing religion. An army and leaders are spawned when these get rolled. In addition, they are hostile to everyone (although battles/sieges that do not involve the target of the revolt do not contribute to the warscore). You can see the revolt risk of a province in the bottom left of the UI.

It seems like you have a normal vassal revolt, and so the armies are only hostile to the duchess. You can check the diplo screen of the duchess and see if you can join in if you want to help out directly.