Is there anyway to break another civ from a vassal treaty?

like a friendly civ you asked to go to war with another civ which you are also at war with but after a few turns the friendly civ gets vassalized. is there any way to liberate it?

If it's capitulated to your "enemy", you could just pound on it's master until it's vassals break away.

oh ya btw is there any way to prevent your allies for DoW me if my vassal is there worst enemy?

Colony/Vassal diplomacy is the most lacking thing in the game, in my mind anyways.

There really isn't a lot you can do with vassals and colonies besides having them.

i have been having trouble with this too, in my present game Mao got about 11 vassals at one point (some by force, others joined him willingly), obviously with that number of vassals he went to the top in the score-power chart; he was so unfairly powerful that any other civ read "i am afraid of their military might" when i tried to make an alliance against him.

Then I massed a huge army to attack him trying to diminish his power, and by declaring war to him I went to war with the 11 vassals too and now all they hate me.

Anyway my military attack was partly succesful, I razed some important cities from him and slowed him in tech considerably. Now I am at the top in the score chart, but any of his vassals broke with him, it is just ridiculous that all the other civs are on his side. I am about getting ICBMs, and i think i will have no choice to nuke this guy to the stone age and see if his vassals understand it is better stay away from this &%(*$#@