What happened in the Fourth Crusade? Why did the Crusaders attack Christian lands instead of Muslim lands?

by Duodenum_Ileum

I read about the Sack of Constantinople a while ago and I never quite understood why the Crusaders did that. I knew the Byzantines were Orthodox and the Crusaders were Catholic, but I thought Orthodox-Catholic relationships were still largely amicable? So what was up with this sudden attack on the Byzantines?

J-Force

I've explained how the omnishambles of the Fourth Crusade occurred here, which also has an excellent list of sources and books from u/WelfOnTheShelf