How about the crusades then?
https://en.wikipedia.org/wiki/Crusades
Ah yes, the biggest mistake in the history of the church.
Those were in the days when the Bible was still only in Latin, Greek and Hebrew. Nobody but the few educated people of the time had any idea what the Bible actually said.
Back in those days, if you were a religeous leader you could pretty much say whatever you want in the name of God and the poor masses would follow you. The masses were purposely misled by the powerful, and that is for dang sure not from the Bible.
You'd be hard pressed to find a sensable Christian now-a-days that will tell you that the crusades were of God or the Bible.