Not content with creating against this prince a new Lombard league, Gregory, impatient to remove him from the midst of European affairs, summoned him to perform the vow which he had taken to go and combat the infidels in Palestine. Frederick embarked, but called back to Brundosium by illness, was excommunicated as a perjurer: he resumed his route, and for proceeding without absolution he was excommunicated anew. He arrives, he compels the sultan of Egypt to abandon Jerusalem, Bethlehem, Nazareth, and Sidon to him, yet, because he treats with an infidel and signs a truce, he is a third time excommunicated. On returning to Europe, he found La Fouille invaded, Italy armed against the empire, and his own son drawn by the pontiff into rebellion and almost into parricide. He triumphed, nevertheless, over so many enemies, arrested and imprisoned his unnatural son, and above all took advantage of a sedition of the Romans against the pope. The Romans who had resumed under Honorius the love of independence, banished Gregory IX. who, compelled to negotiate with the emperor, consented to absolve him for a large sum of money. But Gregory, among other pretensions, claimed Sardinia as a domain of the Holy See. Frederick claimed it as a fief of the empire. Now follows a fourth excommunication, in which Gregory, by the authority of ‘Father, Son and Holy Ghost,’ the authority of the apostles and his own, anathematizes ‘Frederick, late emperor,’ looses from their oaths those who had sworn fidelity to him, and forbids them to recognize him as sovereign. This bull, sent to all monarchs, lords, and prelates of Christendom, was accompanied by a circular letter, which commands the publication of the anathema, to the sound of bells, throughout all the churches. Various writings of the Holy Father²³⁴ represent Frederick as one of the monarchs described in the Apocalypse; political and religious crimes of every species are imputed to this prince by him, even that of having termed Moses, Jesus, and Mahomet, three impostors. Frederick stooped to reply to this torrent of accusation and insult; and that the apology should correspond with the accusation, he treated Gregory as Balaam, as Antichrist, the great dragon, the prince of darkness. By a special epistle²³⁵ to the king of France, Louis IX. or St. Louis the pope offered the empire to the brother of this monarch, Robert count of Artois, on condition that the French should make a crusade against Frederick. St. Louis replied, that he saw with astonishment a pope attempt to depose an emperor; that such a power belonged to a general council alone, and only on the plea of the acknowledged unworthiness of the sovereign; that Frederick on the contrary appeared irreproachable; that he had exposed himself to the dangers of war and of the sea, for the service of Jesus Christ, while Gregory, his implacable enemy, took advantage of his absence to plunder him of his States; that the pope, counting for nothing the rivers of blood which had flowed to satisfy his ambition or his vengeance, wished to subject the emperor, for the sole purpose of afterwards subjugating all the other sovereigns; that his offers proceeded less from a predilection for the French, than from inveterate hatred for Frederick; that he would, however, make inquiry as to the orthodoxy of this prince, and if he proved a heretic, would make the most implacable war against him, as in such case he would not fear doing with the pope himself. This epistle, without doubt, mingled errors of the grossest kind with the expression of the most generous resolutions. What! an assembly of priests possess the right of dethroning a sovereign! What! the religious opinions of a prince be a sufficient motive, with those who did not possess the same, to declare war against him! Yes, such were the indisputable results of those decretals from which the popes had compiled the public law of Christendom.