At that period the principle of hereditary succession was not very clearly ascertained either in Europe or in Asia; and the vast monarchy which Saladin had been enabled to consolidate was broken in pieces at his death. Saif Eddin, his brother, took possession of the greater part of Syria, and strengthened himself by the soldiers of his dead relative, who both loved and esteemed him. Three of the great monarch's sons seized upon such portions of their father's dominions as they could reach; and civil dissensions followed, highly detrimental to the power of the Moslem, and favourable to the security of the Christians. This, indeed, was the moment when a crusade was most practicable, and Pope Celestine III. exhorted all Christendom to snatch the opportunity. In most instances his call fell upon cold and unwilling ears. Philip Augustus was too deeply engaged in those vast and magnificent schemes which, however impeded by the prejudices of the day, rendered his reign a great epoch in the history of nations.[726] Richard Coeur de Lion had learned the danger of quitting his own kingdom, and the vanity of hoping for union among ambitious men. Henry of Germany alone, moved by wild schemes for aggrandizing his territories, assented at once to the crusade; but finding that Sicily seemed ready to receive him, he deemed the nearer conquest the more advisable; and on the same principle he had taken the Cross, he abandoned it again. Not so his subjects; an immense number of the vassals followed eagerly the road which he had quitted;[727] and several Teutonic bishops, with the Dukes of Saxony, Brabant, and Bavaria, set out from Germany, and reached Acre in safety.