Pope Stephen II
In April of 756 AD, Pepin, King of France, accompanied by Pope Stephen II entered northern Italy, forcing the Lombard King Aistulf to lift his siege of Rome, and return to Pavia. Following Aistulf's capitulation, Pepin gave the newly conquered territories to the Papacy by means of the Donation of Pepin, thereby elevating the Pope from being a subject of the Byzantine Empire to head of state, with temporal power over the newly constituted Papal States.