I heard that the First Crusade was a response to Christians being persecuted? Were there systematic persecution towards them or any widespread attacks? Or was the Crusades just to help the Byzantine Emperor but it devolved into something else?
This is a pretty complex topic and it seems like academics have been writing about it forever, so there's always lots more to say. But we have some previous answers in the FAQ that may help:
Who started the Crusades? (Each one) by /u/Ambarenya
What kind of specific examples/evidence exists to support the idea that the Crusades were motivated more by the prospect of collateral wealth rather than religious goals in the Holy Land? by /u/Medievalismist
I saw this article about the Crusades posted on Facebook. How accurate are the bullet points? by /u/Valkine and /u/labarge3
Were the crusades an inevitable event, or were they purely the brainchild of Pope Urban? by /u/thejukeboxhero
Were the Crusades a defensive move? by /u/thejukeboxhero
And also one by me: