Chosroës, eleventh king of Persia, after having conquered Syria, Palestine, and the greater part of Asia, attacked Egypt, surprised Pelusium, and advanced as far as Alexandria without obstacle. The city might certainly have been supported by its fleet, but the archbishop and prefect had employed all the vessels in carrying themselves and their enormous wealth to a place of safety in the isle of Cyprus. Chosroës entered this second city of the Greek empire in triumph, and found in it almost incalculable riches. Heraclius sued for peace, which Chosroës granted, but only with a view of preparing for a fresh war. This recommenced in 627. The haughty Chosroës was conquered; his own son caused him to be killed, and restored to the emperor Heraclius all his father’s conquests. Thus Egypt returned, but for a very short time, under the Roman domination. FOURTH SIEGE, A.D. 640. Mahomet, who was destined to subdue, by his arms and his religion, half the globe as then known, had made himself master of Arabia. His successors thought it their duty to extend his opinions and his conquests. Amrou, the lieutenant of the caliph Omar, took possession of Palestine, and entered Egypt. He employed thirty days in the siege of Pelusium, and then advanced to the ruins of Heliopolis. Thence he proceeded to ancient Memphis, called the Widow of her Kings, after she was eclipsed by her rival Alexandria: her palaces and temples were sinking into ruins. The two banks of the Nile, here three thousand feet wide, were united by two bridges of sixty-three boats, connected by the little isle of Honda, standing in the middle of the river, and covered with gardens and delightful habitations. At the eastern extremity of the bridge was the city of Babylon, and the camp of a Roman legion defended the passage of the river and the second city of Egypt. Amrou laid siege to this fortress, which might be considered as a part of Memphis. After a siege of seven months, the place was carried by assault. The Greeks, on retiring from Upper Egypt, occupied all the important places of the Delta, but were driven out of them in twenty-two days by Amrou. At length Amrou commenced the siege of Alexandria. This first commercial city in the world was abundantly supplied with all the means of defence and subsistence: the sea was always open to it. If Heraclius could have been roused from his lethargy, considerable reinforcements might have been sent to support the besieged. Alexandria itself furnished excellent means of defence; the two great sides of the long square which it forms being covered by the sea and the lake Mareotis, the fronts of attack were narrow, and easily defended. Amrou, however, never ceased to excite the courage of the besiegers by sending them fresh reinforcements daily. The Egyptians at the same time, tired of the domination of the Greeks, and believing they should be better treated by new masters, devoted themselves to the service of Amrou. The Saracens fought like lions.