I have read of so many conflicts between secular rulers and the Pope during the middle ages, how were these conflicts with the highest religious authority? | AskHistorians Archive Observer

I have read of so many conflicts between secular rulers and the Pope during the middle ages, how were these conflicts with the highest religious authority?

by notbobby125

From the Investurture Crisis to actual wars, how did the Barons/Dukes/Doges/Kings/Emperors justify their conflicts with the Papacy?

AlviseFalier

Although there's certainly more to be said, I did write this very cursory answer mostly focusing on the Italian dimension which you might be interested in. I'd also be more than happy to answer follow-ups.