Nor did the election of Frederick II. diminish the power of Pr̆emysl. His influence had considerably contributed to that election; and Frederick’s lifelong war against popes and priests compelled him to rely on any friend who would stand by him against those dangerous antagonists. In his eagerness to secure Pr̆emysl’s help, the Emperor confirmed to the Bohemian crown those German territories in Silesia and the Lausitz, which had so long been the subject of dispute. He also granted to Pr̆emysl the power of appointing bishops in Bohemia without any outside interference. Pr̆emysl’s sympathies with Frederick were further quickened by the struggles with the clergy of Bohemia in which he found himself involved. The same difficulties which our Henry II. had so recently experienced, in his attempts to bring the clergy under the authority of lay tribunals, were harassing Pr̆emysl during a large part of his reign; and his attitude in these matters provoked against him Papal censures as stern as those which were aimed at his Imperial ally. The contest between king and priest in Bohemia ended in a compromise; but the substantial victory probably remained with the king. Pr̆emysl’s vigour tended, no doubt, to reconcile the discontented nobles to his rule; but, in the reign of his son Wenceslaus, the opposition again began to make head. Young Pr̆emysl Ottakar, the son of Wenceslaus, had been appointed Margrave of Moravia; and the power connected with this office induced the nobles to make the young prince the centre of their intrigues. The terrible events of 1241 suppressed faction for a time in Bohemia; for in that year the invasion of Genghis Khan shook all the States of Europe to their centre, and gradually forced into the background any minor cause of division. The details of this invasion are more properly connected with the events to be dealt with in the following chapter. Here it is enough to say that the panic produced by this invasion enabled Wenceslaus to rally round him the whole forces of the kingdom, and to establish the reputation of Bohemia as the champion of European civilisation. But there was one ruler, in whom neither fear of danger nor gratitude for deliverance could quench his hostility to the Slavonic kingdom. This was Frederick of Babenberg, Duke of Austria, who was otherwise known as Frederick the Quarrelsome. Ever since the time when Vratislav had defeated the Margrave Leopold in his rising against Henry IV., the rulers of Austria had been doubtful friends to Bohemia; and, though accident might sometimes have forced them into an alliance, their ordinary attitude was that of suspicion, if not of open hostility. Frederick the Quarrelsome was one of the bitterest in his opposition. He invaded Moravia in the very year after the repulse of the Mongols; and he continued the struggle till his death.