It can only have been on account of the other wars which pressed upon him and occupied him during his remaining years, that Cyrus did not march in person against Amasis. First, the conquest of the nations between the Caspian and the Indian Ocean detained him; and after this, a danger showed itself on his north-eastern frontier which required all his attention, and in meeting which he lost his life. The independent tribes beyond the Oxus and the Jaxartes have through all history been an annoyance and a peril to the power which rules over the Iranian plateau, and it was in repelling an attack in this quarter that Cyrus fell. Amasis, perhaps, congratulated himself on the defeat and death of the great warrior king; but Egypt would, perhaps, have suffered less had the invasion, which was sure to come, been conducted by the noble, magnanimous, and merciful Cyrus, than she actually endured at the hands of the impulsive tyrannical, and half-mad Cambyses. The first step taken by Cambyses, who succeeded his father Cyrus in B.C. 529, was to reduce Phœnicia under his power. The support of a fleet was of immense importance to an army about to attack Egypt, both for the purpose of conveying water and stores, and of giving command over the mouths of the Nile, so that the great cities, Pelusium, Tanis, Saïs, Bubastis, Memphis, might be blockaded both by land and water. Persia, up to the accession of Cambyses, had (so to speak) no fleet. Cambyses, by threatening the Phœnician cities on the land side, succeeded in inducing them to submit to him; he then, with their aid, detached Cyprus from her Egyptian masters, and obtained the further assistance of a Cypriote squadron. Some Greek ships also gave their services, and the result was that he had the entire command of the sea, and was able to hold possession of all the Nile mouths, and to bring his fleet up the river to the very walls of Memphis. Still, there were difficulties to overcome in respect of the passage of an army. Egypt is separated from Palestine by a considerable tract of waterless desert and it was necessary to convey by sea, or on the backs of camels, all the water required for the troops, for the camp-followers, and for the baggage animals. A numerous camel corps was indispensable for the conveyance, and the Persians, though employing camels on their expeditions, are not likely to have possessed any very considerable number of these beasts. At any rate, it was extremely convenient to find a fresh and abundant supply of camels on the spot, together with abundant water-skins. This good fortune befell the Persian monarch, who was able to make an alliance with the sheikh of the most powerful Bedouin tribe of the region, who undertook the entire responsibility of the water supply. He thus crossed the desert without disaster or suffering, and brought his entire force intact to the Pelusiac branch of the Nile, near the point where it poured its waters into the Mediterranean Sea.