Charlemagne was a king and wanted to create a christian empire Charlemagne gave the pope protection and Charlemagne was reward by the pope by being crowned holy roman empire as a result the pope won power to crown the emperor which angered the Byzantium empire .
he terrified pope fled across the alps to the safety of Charlemagne´s court a few months later Leo returned to Rome under the kings protection.
pope Gregory had strong ideas about the powers of the pope he issued the list of rules declaring his supreme authority over both church and secular leaders Gregory declared the pope alone had the power to choose bishops and claimed to have power to remove emperors form the throne.
pope Gregory and King Henry were direct attack on their own power. pope Gregory and king Henry had excommunication and the pope freed Henry's subjects from their oaths of loyalty to the emperor. people across Europe reacted by putting effort to end the excommunication.
the conflict between pope Gregory and king Henry did not end. the concordat worms gave they sole authority to appoint the bishop. this was not a success because pope Gregory forgave king Henry but the conflict still continued.
after Charlemagne empire collapsed the German lands to the east were divided among number of dukes. following Germanic tradition they chose one of their own to be king in many cases the Germanic king had little power over the other novels.