his hereditary estates. In 1235 the establishment of the Duchy of Brunswick-Lüneburg, in favour of the Guelfic house, secured for it a permanent position among the territorial powers of northern Germany. The higher aspirations of the descendants of Henry the Lion perished for ever on the fatal field of Bouvines. Frederick II. was now undisputed King of the Romans, and Innocent III. had won another great triumph. By the Golden Bull of Eger (July 1213) Frederick had already renewed the concessions made by Otto to the Church, and promised obedience to the Holy See. In 1216 he pledged himself to separate Sicily from the Empire, and establish his son Henry there as king, under the supremacy of the Church. But like his other triumphs, Innocent’s victory over the Empire was purchased at no small cost. For the first time, a German national irritation at the aggressions of the Papacy began to be distinctly felt. It found an adequate expression in the indignant verses of Walter von der Vogelweide, protesting against the priests who strove to upset the rights of the laity, and denouncing the greed and pride of the foreigners who profited by the humiliation of Germany. [Sidenote: Innocent III. and the Crusades.] Amidst all the distractions of Western politics, Innocent III. ardently strove to revive the crusading spirit. He never succeeded in raising all Europe, as several of his predecessors had done. But after great efforts, the eloquent preaching of Fulk of Neuilly stirred up a fair amount of enthusiasm for the crusading cause, and, in 1204, a considerable crusading army, mainly French, mustered at Venice. It was the bitterest disappointment of Innocent’s life that the Fourth Crusade [see chapter xv.] never reached Palestine, but was diverted to the conquest of the Greek Empire. Yet the establishment of a Catholic Latin Empire at Constantinople, at the expense of the Greek schismatics, was no small triumph. Not disheartened by his first failure, Innocent still urged upon Europe the need of the holy war. If no expedition against the Saracens of Syria marked the result of his efforts, his pontificate saw the extension of the crusading movement to other lands. Innocent preached the Crusade against the Moors of Spain, and rejoiced in the news of the momentous victory of the Christians at Navas de Tolosa [see chapter xx.]. He saw the beginnings of a fresh Crusade against the obstinate heathen on the eastern shores of the Baltic. But all these Crusades were against pagans and infidels. [Sidenote: Extension of the crusading idea.] Innocent made a much greater new departure when he proclaimed the first Crusade directed against a Christian land. The Albigensian Crusade, which can more profitably be described when we deal with the development of the French monarchy [see chapter xvii.], succeeded in destroying the most dangerous and widespread popular heresy that Christianity had witnessed since the fall of the Roman Empire, and