Pope Hadrian I (772–95) changed the dating custom used by the popes. He began dating his administrative documents and correspondence not by the regnal year of the emperor in Constantinople, but by the year of his own period in office and by the regnal year of the King of the Franks. By now this was the son of Pippin, Charles, the first Frankish king to visit Rome, during the military campaign of 774 which crippled Lombard power. Charles’s reign was long, 768 to 814, and history soon christened him Charles the Great, Carolus Magnus – Charlemagne.
