To us, as we look back, nothing seems more natural than that the great Frankish king, after the conquest of Italy, should have brushed aside the theoretical difficulty of an existing Roman Empire and assumed the Imperial title, Emperor of the Romans. History moves more slowly. Charlemagne was a Frank, accustomed to Frankish usages and ideas; he hesitated to adopt formally a wholly different conception of sovereignty and society. His nobles probably agreed with the advice given by Pope Zacharias to Pippin, that the man who held the power should receive the corresponding title, but being Franks they thought the dignity of Frankish king sufficient. So matters stood with nothing between Charlemagne and the Imperial crown but a theoretic difficulty, and a certain reluctance. Unexpectedly and in quick succession, events in Constantinople swept away the theoretic difficulty, and events in Rome gave the Pope sufficient energy to overcome the reluctance. At Constantinople, the dowager Empress blinded and deposed her son the Emperor (797), and assumed to rule as sole _Augusta_. This wickedness, and the ancient doctrine that, though a woman might lawfully share the Imperial throne, she might not reign alone, combined to render plausible a theory readily adopted in the West, that the Imperial throne had become vacant. The event in Rome was this. A savage gang of nobles and ecclesiasts attacked Pope Leo III in the street, beat him, half-blinded him, cut his tongue, and imprisoned him in a monastery (799). He escaped and fled to Charlemagne in Germany. His enemies followed and charged him with various crimes. Charlemagne sent him back to Rome in the company of some great nobles, who were commissioned to investigate the charges, and went himself also. There, in St. Peter's basilica, in the presence of Frankish nobles and Roman ecclesiasts, with Charlemagne presiding, the Pope took a solemn oath of innocence (December 4, 800). Such an oath according to the jurisprudence of the time was necessarily followed by acquittal; and the Pope's innocence necessarily proved the guilt of his accusers, who were punished. Such crimes, east and west, were insufferable. Something had to be done. Everybody looked to Charlemagne. His position as head of Christendom was acknowledged even beyond the bounds of western Europe. The Patriarch of Jerusalem, a subject of the Caliph Haroun al Raschid, sent to Charlemagne the keys of Calvary and of the Holy Sepulchre and the banner of the Holy City. Obviously it was time for the Imperial dignity to be added to Imperial power.