History can hardly boast of another example of so gigantic a conquest during so short a period as that gained by the first adherents of Islam. Like the fiery wind of the desert, they had broken from their retreats, animated by the promises of the Prophet, and spread the new doctrine far and wide. In 653 the scimitar of the Saracens enclosed an area as large as the Roman Empire under the C¾sars. Barely forty years elapsed after the death of the Prophet when the armies of Islam reached the Atlantic. Okba, the wild and gallant leader, rode into the sea on the western shore of Africa, and, whilst the seething waves reached to the saddle of his camel, he exclaimed: "Allah, I call thee as witness that I should have carried the knowledge of Thy name still farther, if these waves threatening to swallow me would not have prevented me from doing so." Not long after this, the flag of the crescent was waving from the Pyrenees to the Chinese mountains. In 711 the Saracens under General Tarik crossed the straits between the Mediterranean and the Atlantic, and landed on the rock which has since been called after him, "the hill of Tarik," Jebel el-Tarik or Gibraltar. Spain was invaded and captured by the Moslems. For awhile it seemed as if on the other side of the Garonne the crescent would also supplant the cross, and only the victory of Charles Martel in 732 put a stop to the wave of Muhammedan conquest. Thus in a brief period Muhammedanism spread from the Nile Valley to the Mediterranean. Muhammed's trenchant argument was the sword. He gave a distinct command to his followers to convince the infidels of the Power of truth on the battle-field. "The sword is a surer argument than books," he said. Accordingly the Koran ordered war against unbelievers: "The sword is the key to heaven and hell; a drop of blood shed in the cause of Allah, a night spent in arms, is of more avail than two months of fasting and prayer; whoever falls in battle, his sins are forgiven, and at the day of judgment his limbs shall be supplied with the wings of angels and cherubim." Before the battle commenced, the commanders reminded the warriors of the beautiful celestial houris who awaited the heroes slain in battle at the gates of Paradise.