History of the papacy (1048–1257)

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. Henry IV's Walk to Canossa in 1077 to meet Pope Gregory VII (1073–85), although not dispositive within the context of the larger dispute, has become legendary.

Source: Wikipedia — History of the papacy (1048–1257) (CC BY-SA 4.0)