In 799, Pope Leo III had been assaulted by some of the Romans, who tried to put out his eyes and tear out his tongue. Leo escaped and fled to Charlemagne at Paderborn. Charlemagne, advised by scholar Alcuin, travelled to Rome, in November 800 and held a synod. On 23 December, Leo swore an oath of innocence to Charlemagne. His position having thereby been weakened, the Pope sought to restore his status. Two days later, at Mass, on Christmas Day (25 December), when Charlemagne knelt at the altar to pray, the Pope crowned him "Imperator Romanorum" ("Emperor of the Romans") in Saint Peter's Basilica. In so doing, the Pope rejected the legitimacy of Empress Irene of Constantinople: