About this time the papal court produced another document, the so-called ‘Donation of Constantine’, in which the first of the Christian emperors apparently granted to the Popes the western half of the Roman Empire. Centuries later this was proved to be a forgery, but for a long while people accepted it as genuine, and the power of the Popes was greatly increased. We do not know how much Charles believed in papal supremacy in temporal matters; but throughout his reign his attitude to the Pope over Italian affairs was rather that of master to servant than the reverse. It was only when spiritual questions were under discussion that he was prepared to yield as if to a higher authority.
When he had reduced Pavia Charlemagne left Lombardy to be ruled by one of his sons and returned to France; but it was not very long before he was called back to Italy, as fresh trouble had arisen there. The cause was the unpopularity of Pope Leo III in Rome and the surrounding country, where turbulent nobles rebelled as often as they could against the papal government. One day, as Leo was riding through the city at the head of a religious procession, a band of armed men rushed out from a side street, separated him from his attendants, dragged him from his horse, and beat him mercilessly, leaving him half dead. It was even said that they put out his eyes and cut off his tongue, but that these were later restored by a miracle.
Leo, at any rate, whole though shaken, succeeded in reaching Charlemagne’s presence, and the King was faced by the problem of going to Rome to restore order. Had it been merely a matter of exacting vengeance, he would have found little difficulty with his army of stalwart Franks behind him; but Leo’s enemies were not slow in bringing forward accusations against their victim that they claimed justified their assault. Charlemagne was thus in an awkward position, for he was too honest a ruler to refuse to hear both sides, and his respect for the papal office could not blind him to the possibility of evil in the acts of the person who held it, especially in the case of an ambitious statesman like Leo III.
He felt that it was his duty to sift the matter to the bottom; and yet by what law could the King of France or even of Italy put Christ’s vice-regent upon his trial and cross-examine him?