What was the conflict between Charlemagne and pope Leo?

The conflict between Charlemagne and Pope Leo III primarily revolved around issues of authority and governance within the Christian Church. Pope Leo, facing opposition in Rome and needing protection, sought Charlemagne's support, which led to Charlemagne aiding him against his enemies. This alliance culminated in Charlemagne's coronation as Emperor of the Romans in 800 AD, symbolizing a significant shift in power dynamics, as it elevated the pope's authority while also solidifying Charlemagne's rule. However, this arrangement also sparked tensions regarding the relationship between secular and ecclesiastical authority.