غريغوري الثالث
In 739, Pope Gregory III addressed a letter to Charles Martel, master of the Frankish kings' royal palace in which appeared, for the first time, the phrase "populus peculiaris beati Petri". The Pope was referring to the population of the duchies of Rome, Ravenna, and the Pentapolis as living together in a republic, of which Saint Peter was the protector and eponymous hero.