Q: Can your own vassal start a war against others by their own?

[Darkrenown]

Do you remember what kind of war it was? Might tell as how they started it. E.g. perhaps someone claimed their throne before they were your vassal and it started a succession war? SHouldn't be possible, but maybe there's a bug.

 

[Darkrenown]

Can't think of anything that would do that, if you have a save please bugreport it.

 

[Darkrenown]

You're pretty much right, except in HttT they can also break their alliance to DoW their Overlord.