It was always an object of first importance with Charlemagne to support the papal authority, as holding out the only means of spreading Christianity, which he justly considered the most effectual instrument he could employ to enlighten and civilize the world. An attempt had been made to mutilate the Pope, and thus disqualify him for his office, by Campulus and Paschal, two disappointed aspirants to the papacy; but he escaped from their hands and brought his complaints before Charlemagne. The conspirators then attempted to justify the deed, by accusing the Pope of atrocious crimes; and the king calling to his aid certain of the Roman prelates, proceeded to sit in judgment on him. The prelates, however, declared that by all the canonical rules they could not judge their superior; and Leo therefore was allowed, according to an old custom, to purge himself, by a solemn oath, of the crimes which had been laid to his charge. Many motives of policy at this time induced the Pope to set up an emperor of the West in opposition to the Eastern Empire. It was Christmas-day, when, with the rest of the Catholic world, Charlemagne presented himself in the church of St. Peter. At the desire of the Romans he was dressed in the long robe of the patrician, and unsuspicious, it is said, of the honor intended him, knelt at the high altar; but, just as he was about to rise, Leo advanced, and suddenly placed upon his head the crown of the Western world, amidst the popular acclamations, "Long life and victory to Charles Augustus, crowned by God, great and pacific Emperor of the Romans!" To end the long-existing feuds between the Western and Eastern Empires, Charlemagne now proposed to marry Irene, who, having deposed her son and put out his eyes, had usurped the throne of Constantinople. Irene herself was not unwilling to accept the offer; but she was overruled by a faction, and a treaty of peace was substituted for a treaty of marriage. But while the negotiations were going on, Irene herself was deposed by the great treasurer, Nicephorus, who even refused to grant her the smallest pittance, so that the degraded empress was obliged to support herself by the labors of the distaff. He was, however, glad to conclude a peace with Charlemagne.