So I was at war with Milan for at least 60 turns, taking their cities and defending. I took their capital, but they still have Venice. The pope calls a crussade and they decided to join. So they built a full army with a 5 star general leading the crusade. They boarded a ship and headed toward the Middle East.
One problem though, I control the waters around that ship. So I just couldn't resist not attacking the fleet even if it was a crusading fleet. I was able to destroy about 3/4 of the fleet, but the rest got away. Anyway the Germans got the city.
I've been excomunicated, but It was worth it. I'm thinking of assasinated the pope once I built a good assasin.