Quote Originally Posted by Ciaran
No, you can´t, which is a damned shame. You know, even Master of Magic, that really ancient game had that option, and it´s diplomacy was way less complex than Rome´s.
Actualy, you can cancel alliances. In the diplomacy screen just hit, 'cancel alliance' and then hit the 'inform ally of changes' button that is right next to the 'give as a gift' button.

I know because I use it all the time. I just cancel an alliance and then attack them with several armies that I had built up in advance. Works like a charm...

Not sure about your other problem though, your protectorates should turn against you if you attack someone that they are allied with. That is one of the many reasons that I avoid them at all costs unless I am in desperate need. They usualy just backstab you anyways. Usualy I just crush the faction and take their land.

If I do actualy take them as my protectorate, I just forget about them and treat them as I would any other neutral faction. If they are in my way, I just take their land and finish them off. If I want their land I take it. They get no special treatment.

It is easier just to take their cities and finish them off than to let them rebuild and attack you again later...