The Holy Roman Empire lasted from the year 800, to the year 1806, nearly 10 decades! According to Wikipedia, “Unsourced material may be challenged and removed. The history of the papacy from 1046 to 1216 was marked by conflict between popes and the Holy Roman Emperor, most prominently the Investiture Controversy, a dispute over who— pope or emperor— could appoint bishops within the Empire.” So one of the main reasons for the conflicts between the emperors and the popes was an argument over who could appoint bishops within the Empire, and who couldn’t. So technically, it was an issue over who had the power and authority to appoint bishops within the Empire (that stuff can tear people apart).