a question about vassel

[echolovesyou]

i am currently having war against a big nation that has 3 vassels states. it is very difficult and hard. fortunately, the big nation itself is not close to me right now, and its 2 of the vassel states are my neighbors. My question is, is it possible that i capture and raze enough of the vassel state's cities so the vassel will leave the strong nation and become capitulated by me?

 

[Refar]

You need to reduce him below 50% of his initial land, then he will break off from the current master. He might or might not capitulate to you after that (often they will say "We are afraid of your Enemy" if you still at war with the former master). In any case, if a Vassal breaks of from the master, you can negotiate fo separate peace treaty.