When in 1326 Louis saw the arrival in Nuremberg of the two authors of the book dedicated to him, startled by the boldness of their political and religious theories, he was at first inclined to treat them as heretics. He soon changed his mind, however, and, admitting them to the circle of his intimates, loaded them with favours. John XXII, for his part, excommunicated him on April 3 1327. Having become one of the chief inspirers of the imperial policy, Marsilius accompanied Louis to Italy, where he preached or circulated written attacks against the pope, especially at Milan, and where he came within the sight of the realization of his wildest utopias. To see a king of the Romans crowned emperor at Rome, not by the pope, but by those who claimed to be the delegates of the people (January 17, 1328), to see John XXII. deposed by the head of the Empire (April 18), and a mendicant friar, Pietro de Corbara, raised by an imperial decree to the throne of St Peter (as Antipope Nicholas V) after a sham of a popular election (May 12), all this was merely the application of principles laid down in the Defensor pacis. The two authors of this book played a most active part in the Roman Revolution. Marsilius, appointed imperial vicar, abused his power to persecute the clergy who had remained faithful to John XXII. In recompense for his services, he seems to have been appointed archbishop of Milan, while his collaborator, John of Jandun, obtained from Louis the bishopric of Ferrara.
Marsilius of Padua also composed a treatise De translatione imperii romani, which is merely a rearrangement of a work of Landolfo Colonna, De jurisdictione imperatoris in causa matrimoniali, intended to prove the exclusive jurisdiction of the emperor in matrimonial affairs, or rather, to justify the intervention of Louis of Bavaria, who, in the interests of his policy, had just annulled the marriage of the son of the king of Bohemia and the countess of Tirol. But, above all, in an unpublished work preserved at Oxford, the Defensor minor, Marsilius completed and elaborated in a curious manner certain points in the doctrine laid down in the Defensor pacis. In it he deals with ecclesiastical jurisdiction, penances, indulgences, crusades and pilgrimages, vows, excommunication, the pope and the council, marriage and divorce. Here his democratic theory still more clearly leads up to a proclamation of the imperial omnipotence.
Text mostly from Encyclopedia Britannica 1911