Already the Saracenic warriors under able leaders had overrun Persia and Syria, and in 637 Omar, their Caliph, after a four months' siege, received the keys and homage of a city, which, though the home of many Christians, was very sacred also in the eyes of the Mohammedans, as a "House of God," a city of saints and miracles, since Mohammed himself had visited it as a prophet and had thence set out for heaven in his nocturnal voyage. During the lifetime of Omar, the Christians escaped serious persecution, but violence and fanaticism increased at a fearful rate under his successors--except for the period (768-814 A. D.) during which reigned Haroun al Raschid, the greatest of all the Saracen Caliphs. In 1076--fateful day--Jerusalem was captured by the Seljukian Turks who had come down from the inner provinces of Asia in resistless numbers--embraced Islamism, and under the banners of the Caliph of Bagdad, had conquered Syria and Palestine. Their entry into Jerusalem was signalized by a terrible massacre of all opponents. The fanatical fury of these barbarians was untempered by any spirit of toleration that had sometimes marked Saracenic civilization,--and soon their wild hordes waved their banners of blood and fire before the very gates of Constantinople. The Emperor Alexius purchased peace by ceding Asia Minor to the victorious Solyman, who at once established his power at Nice and began building a fleet for the capture of the Byzantine capital. All Europe was roused and smitten with alarm. The hour had come for the Greek and the Latin churches to unite all their power for the defence of their common faith and preserve their empires from being devastated by the barbarian Turks. Pope Gregory began to exhort the sovereigns of Europe to arm against the infidel: when suddenly from an anchorite's cell appeared a monk who fired with enthusiasm the heart of all Europe and blew into fiercest blaze all the fanatical elements of a religious war. It was reserved for a poor pilgrim who had found refuge in a cloister from the ridicule and follies of a wicked world to become the instrument of converting the zeal of pilgrimage into the fury of an armed crusade. This man was Peter the Hermit.