However, Charlemagne's relationship with the papacy was not always smooth. He frequently intervened in papal elections, and he sometimes disagreed with the pope on theological matters. In 800, he was crowned Holy Roman Emperor by Pope Leo III, which further strengthened his ties to the papacy. However, this also led to tensions between Charlemagne and the Byzantine Empire, which considered itself to be the true heir to the Roman Empire.
Overall, Charlemagne's relationship with the papacy was one of mutual respect and cooperation, but it was also marked by occasional conflict and tension.