A struggle began immediately on the accession of Michael and soon became a curiously complicated strife. The pope in 1262 proclaimed a Crusade against him and against the Genoese, who still remained allied with him. The pontiff characterised Michael as a usurper and a schismatic, and granted the same indulgences to those who took up arms or contributed to the expenses of the expedition against him as to those who fought for the deliverance of the Holy Land. He urged St. Louis to collect tithes for the same purpose.[26] Michael, on the other hand, while preparing to resist invasion and strengthening the city walls, increasing his fleet, and raising new levies, yet sought to satisfy the pope by offering to do his utmost to bring about the Union of the Churches. Possibly owing to the emperor’s representations, Urban the Fourth countermanded the proposed expedition, diverting it against the Tartars who were then invading Palestine. He sent friars to Constantinople to exhort the emperor to carry out his proposal for reunion. His successor, Clement, was, however, a man of a different spirit and replied to the promises of Michael that they were only fair words intended to prevent him from aiding the dethroned Baldwin. While Michael had undoubtedly this object in view, he seems to have been sincere in his desire for Union. One of his objections to the patriarch Arsenius was that he would have nothing to do with the Latins. The Greek priests clamoured to such an extent against the patriarch who succeeded Arsenius, because he was believed to be willing to follow the emperor’s example in working for Union, that he was compelled to resign.