Of the details of his proposed invasion nothing is known beyond the fact that his original scheme must have been considerably modified as he penetrated farther into Asia. His geographical knowledge of the interior of the empire could hardly have been sufficient for an orderly mapping out beforehand of the course he actually took. That was entirely governed by the extraordinary series of events which marked the various stages of his expedition. His design was to dethrone the Persian king and secure possession of the country. To do this effectively the first step was to conquer Asia Minor, to get under his control the remoter provinces of Syria and Egypt, and then to advance on Babylon and Susa. That there was immediate necessity for setting his army on the march was plain to him, because of the dangerous position of the Macedonian forces already in Asia Minor. The Persian general, Memnon, had checkmated Parmenio, who was recalled, and the prospects of Macedonian success were blighted by the defeat of another Macedonian general Kallás in the Troad. Before Alexander left his own kingdom, the authority of the Persian government had been generally restored throughout the whole of Asia Minor. In the spring of 334, Alexander marched to the Hellespont with an army numbering altogether 30,000 infantry and 4500 cavalry. Of these, 12,000 infantry and 1500 cavalry were from Macedon; contingents from the allies made up the rest. There were besides 160 warships, of which Athens furnished twenty. Alexander’s chief military adviser was Parmenio, whom Philip, his father, had declared to be the only Macedonian general he had discovered in many years. Of the subordinate officers the most noteworthy were Philotas, who was in command of the Macedonian cavalry, and Nikanor, who led the álite of the Macedonian infantry (the so-called Hypaspistæ, or the Bodyguards). During the absence of the king, the administration of Macedon and of the subject states was left in the hands of Antipater. The incompetence of the Persians in aggressive resistance was manifest from the first. They were far superior to the Greeks at sea, and if they had made intelligent use of their fleet they could have prevented Alexander’s army from crossing the Hellespont. Indeed, orders had been issued the year before to the coast cities that their ships should be kept in readiness in anticipation of an invasion. But so slipshod was the administration in the loosely governed provinces of Persia that their great fleet was unable to put to sea when Alexander reached the narrow arm of water which divides Europe from Asia. He had no difficulty in passing; indeed Parmenio was left to superintend this operation, while the young king visited the cities of the Troad rich in legendary lore, and made a pilgrimage to the tomb of his reputed ancestor, Achilles.