But Nicholas was only able to give a German prince once more a footing in Italy because Rudolf had been effectually barred from reviving the Hohenstaufen claims. Already at the Council of Lyons the envoys of Rudolf had appeared and in his name had taken the oaths previously exacted from Otto IV and Frederick II. Rudolf had subsequently met Pope Gregory at Lausanne in 1275, and had confirmed the act of his representatives. Thus Gregory obtained from a crowned German King an acknowledgment of all the claims advanced by the Papacy since the days of Charles the Great. Rudolf was too busy ever to visit Rome; but in negotiations with regard to his coronation as Emperor, Nicholas III exacted the confirmation of all that was promised to Gregory, and this included especially the lands of the old Exarchate and the district of Pentapolis, which had never yet been actually in the hands of papal officers. [Sidenote: Martin IV (1281-5).] Dante has banned the memory of Nicholas as the simoniacal Pope. He certainly used his enormous patronage to enrich his own family. But his death (August, 1280) nearly proved fatal to the freedom of Europe; for Charles at length obtained his own nominee to the Papacy in the person of a Frenchman, Martin IV, who proceeded to hand over to the King for life the Roman senatorship conferred upon the Pope. All the work of the preceding Popes was undone. The temporary union of the Churches was dissolved by the excommunication of the Greek Emperor on the pretext that he had not carried out his promises; and Charles, who had obtained a footing in the Greek peninsula and made a league with Venice, prepared to start on his expedition against Constantinople. There seemed every prospect of his success. [Sidenote: Sicilian Vespers]