In the middle of a war with the HRE and the Byzantine Empire (you wouldn't believe the look on my face when I read "Kaiser what's-his-face has called the Byzantine Empire into the Italian-Holy Roman De-Jure War", my fucking vassals decide to present an ultimatum. Now I've been nice enough to let these slide in the past, but coming in the middle of a war (actually towards the end, but still) pissed me right the fuck off. The bastards are out for the one council law I still have, Banishment. Now I have no interest or desire to have banishment, but its the very last thing I have as ruler so I tell them to piss off.
They revolt. Much of North Italy revolts, along with Brandenburg and all of our territory in Anatolia. Outrageously, the son of my previous ruler joined the revolt (elective). He was the previous heir, but I nominated the Duchess of Sicily when it became clear she was more popular then him in Italy (amusingly, when the Duchess of Sicily took over she was in the process of trying to seduce him, which I would have let continue had the civil war not occured). Unfortunately he was awarded the Kingdom of Anatolia for his troubles (I actually had to found Italia purely to prevent him from breaking off), so now this ungrateful little shit is revolting.
Jokes on them. I had already raised my vassal armies from them, and my armies were right on the edge of Italian territory, so it wasn't hard to smash their armies before they got together and siege down the provinces of the ungrateful dukes responsible. The best part is that I started the war with the HRE in order to get some prisoners to test out the new torture, mutilate, and execution methods from the DLC, and now I have more than enough unwilling test subjects. I think I will mutilate the ringleader to give him a little memento of the price of disobedience, revoke the Kingdom of Anatolia, and execute or torture those who remain, with the exception of the Duchess of Lombardy. I need her alive. I killed off her older brother so that a female would inherit so that I could marry someone off to her and get the duchy back under family control (which is how we lost it in the first place). She needs to be alive and healthy to have a son, plus I'd like the "merciful" modifier while I engage in some minor tyranny.