Leo III, Saint, pope (795–816), a Roman; successor of Adrian I. He was attacked about the face and eyes by members of Adrian's family, who hoped to render him unfit for the papacy. Leo recovered and fled (799) to Charlemagne's protection at Paderborn. In 800, Charlemagne went to Rome and conducted a trial during which Leo successfully defended himself against charges of misconduct made by his enemies. On Christmas day, 800, Leo crowned Charlemagne emperor, the event that traditionally marks the beginning of the Holy Roman Empire. Leo's successor, Stephen IV, crowned Charlemagne's son, Louis the Pious, and thus was established the papal claim to the right to consecrate the emperor. In the East-West controversy over the Procession of the Holy Spirit, Leo declared that the Filioque of the creed was dogmatically necessary but liturgically dispensable, and he recommended its omission in the name of East-West unity. Leo did much to beautify Christian Rome. He was canonized in 1673. Feast: June 12.