How did the popes gain political power in Rome during the early Middle Ages?

During the early Middle Ages, the popes gradually transitioned from religious leaders to secular rulers in Rome as the authority of the Byzantine Empire in Italy declined.123

The Shift in Authority

As imperial control weakened, the responsibility for civil administration and the protection of Rome shifted from the Roman Senate and distant Byzantine exarchs to the papacy. Figures like Gregory I played a pivotal role by managing urban administration and organizing defenses against Lombard threats. By the 8th century, the popes increasingly sought autonomy due to religious disagreements with the Byzantine emperor—specifically over iconoclasm—and the empire's failure to provide adequate military support.231

Alliance with the Franks

To secure their position against the Lombards, the popes turned to the Frankish monarchy. This alliance was solidified by the Donation of Pippin in 756, in which King Pippin III granted the pope rights over territories in central Italy. This act provided the theoretical foundation for the papacy's temporal power and the formation of the Papal States, a status later confirmed and expanded by Charlemagne and his successors.124