ATTACKS UPON CONSTANTINOPLE.--Only fifty years had now passed since the death of Mohammed, but during this short time his standard had been carried by the lieutenants of his successors through Asia to the Hellespont on the one side, and across Africa to the Straits of Gibraltar on the other. From each of these two points, so remote from each other, the fanatic warriors of the desert were casting longing glances across those narrow passages of water which alone separated them from the single continent that their swift coursers had not yet traversed, or whence the spoil of the unbelievers had not yet been borne to the feet of the Vicar of the Prophet of God. We may expect to see the Saracens at one or both of these points attempt the invasion of Europe. The first attempt was made in the East (in 668), where the Arabs endeavored to gain control of the Bosporus, by wresting Constantinople from the hands of the Eastern emperors. But the capital was saved through the use, by the besieged, of a certain bituminous compound, called Greek Fire. In 716, the city was again besieged by a powerful Moslem army; but its heroic defence by the Emperor Leo III. saved the capital for several centuries longer to the Christian world. THE CONQUEST OF SPAIN (711).--While the Moslems were thus being repulsed from Europe at its eastern extremity, the gates of the continent were opened to them by treachery at the western, and they gained a foothold in Spain. At the great battle of Xeres (711), Roderic, the last of the Visigothic kings, was hopelessly defeated, and all the peninsula, save some mountainous regions in the northwest, quickly submitted to the invaders. Thus some of the fairest provinces of Europe were lost to Christendom for a period of nearly eight hundred years. No sooner had the subjugation of the country been effected than multitudes of colonists from Arabia, Syria, and North Africa crowded into the peninsula, until in a short time the provinces of Seville, Cordova, Toledo, and Granada became Arabic in dress, manners, language, and religion. INVASION OF FRANCE: BATTLE OF TOURS (732).--Four or five years after the conquest of Spain, the Saracens crossed the Pyrenees, and established themselves upon the plains of Gaul. This advance of the Moslem hosts beyond the northern wall of Spain was viewed with the greatest alarm by all Christendom. It looked as though the followers of Mohammed would soon possess all the continent. As Draper pictures it, the Crescent, lying in a vast semi-circle upon the northern shore of Africa and the curving coast of Asia, with one horn touching the Bosporus and the other the Straits of Gibraltar, seemed about to round to the full and overspread all Europe.