The pious design was approved by the companions of Mahomet and the chiefs of the tribes; and twenty thousand Arabs marched from Medina, with the gifts and the blessing of the commander of the faithful. They were joined in the camp of Memphis by twenty thousand of their countrymen; and the conduct of the war was intrusted to Abdallah, 139 the son of Said and the foster-brother of the caliph, who had lately supplanted the conqueror and lieutenant of Egypt. Yet the favor of the prince, and the merit of his favorite, could not obliterate the guilt of his apostasy. The early conversion of Abdallah, and his skilful pen, had recommended him to the important office of transcribing the sheets of the Koran: he betrayed his trust, corrupted the text, derided the errors which he had made, and fled to Mecca to escape the justice, and expose the ignorance, of the apostle. After the conquest of Mecca, he fell prostrate at the feet of Mahomet; his tears, and the entreaties of Othman, extorted a reluctant pardon; but the prophet declared that he had so long hesitated, to allow time for some zealous disciple to avenge his injury in the blood of the apostate. With apparent fidelity and effective merit, he served the religion which it was no longer his interest to desert: his birth and talents gave him an honorable rank among the Koreish; and, in a nation of cavalry, Abdallah was renowned as the boldest and most dexterous horseman of Arabia. At the head of forty thousand Moslems, he advanced from Egypt into the unknown countries of the West. The sands of Barca might be impervious to a Roman legion but the Arabs were attended by their faithful camels; and the natives of the desert beheld without terror the familiar aspect of the soil and climate. After a painful march, they pitched their tents before the walls of Tripoli, 140 a maritime city in which the name, the wealth, and the inhabitants of the province had gradually centred, and which now maintains the third rank among the states of Barbary. A reenforcement of Greeks was surprised and cut in pieces on the sea-shore; but the fortifications of Tripoli resisted the first assaults; and the Saracens were tempted by the approach of the praefect Gregory 141 to relinquish the labors of the siege for the perils and the hopes of a decisive action. If his standard was followed by one hundred and twenty thousand men, the regular bands of the empire must have been lost in the naked and disorderly crowd of Africans and Moors, who formed the strength, or rather the numbers, of his host. He rejected with indignation the option of the Koran or the tribute; and during several days the two armies were fiercely engaged from the dawn of light to