Co-belligerence - how it works?

[Esik]

I dont really know how Co-belligerence works. For easy example: I am Austria and i want to attack France. France is allied with England. England is allied with Scotland. So if i declare war to France, England will joing them in war and what happen when i check or uncheck England as Co-belligerence?

 

[LeKaiser]

If you leave England unchecked:
- England's allies, e.g. Scotland, will not be called in
- taking English provinces in the war will be twice as expensive, in both warscore and aggressive expansion

If you check England as a co-belligerent:
- England's allies will be called in
- You can take English provinces at normal warscore and AE cost

 

[Esik]

Thanks a lot!

 

[Kergan]

If you check England as a co-belligerent:
- England's allies will be called in
- You can take English provinces at normal warscore and AE cost

There are a few additional subtle twists on that last point. To raise but two:

- It'll also cost you the same and produce AE as normal when you separate peace England for conquest wars - just as if you had declared a war on England itself and peaces it out. But you'll end up with slightly less AE if you peace out both co-belligerents together.
- If you use the reconquest CB on two targets at the same time, you won't pay diplo points to return cores from either co-belligerents if you peace them out at the same time. But you'll end up paying diplo points, and lots more AE, if you separate peace out the co-belligerent and use return core on it.

 

[Viktor Vaughn]

Also note that you can't call someone as a co-belligerent if you already have a truce with that country. They'll probably still join the war, but it will only be as a normal ally.

 

[Brynjar]

It's also worth noting that the co-belligerent's allies will accept/decline call to war as normal, so you can check if Scotland will actually join by going to the declare war screen against England.