He first came into conflict with the Persians on the banks of the Granîkos, a small river, which, flowing from Mount Ida through the Trojan plain, enters the Propontis to the west of Kyzikos. Their army, which consisted of 20,000 horse, and an equal number of Greek mercenaries, was commanded by several satraps who were assisted by the counsels of Memnon the Rhodian, the ablest general in the service of Darius. The Persians were drawn up in line along the right bank of the stream, while their mercenaries were posted on a range of heights that rose in the rear. Alexander drew up his forces on the opposite bank in the order which he adopted in all his great battles. Thus the phalanx formed his centre; he commanded himself the extreme right, and the officer in whom he had most confidence the extreme left. To either wing were attached such brigades of the phalanx as circumstances seemed to require. The Persians having observed where Alexander was posted, strengthened their left wing with dense squadrons of their best cavalry, anticipating that this part of their line would be exposed to the first fury of the onset led by himself in person. They judged aright. Alexander having sent a detachment of cavalry across the stream, followed with other cavalry and a portion of the phalanx. The Persians made a gallant resistance, but were soon beaten. Their darts and scimitars were no match for the tough cornel of the Macedonian spears. Their ranks first broke where Alexander himself in the hottest of the fight was dealing death and wounds around him. A blow which was descending on his own head, and which if delivered would have proved fatal, was intercepted by Kleitos, who cut off the arm of the assailant, scimitar and all. The field was won before either the phalanx on the one side, or the Greek mercenaries on the other, could come into action. The Macedonians, after returning from a short pursuit, closed around the mercenaries and cut them down, all but 2000 who were made prisoners and sent in chains to Macedonia. The number of the Persians slain was about 1000 against only 115 on the other side. Alexander did not, like most other conquerors after a victory, plunder the surrounding country, but regarding Asia as already his own, treated the inhabitants as subjects whose interests he was bound to protect and promote. Neither did he at once advance into the interior, but, acting by a rule of strategy which he was always careful to observe, resolved to make his rear secure. He therefore first reduced all the western provinces of the empire which Darius after the defeat of his satraps had placed under the supreme authority of Memnon the Rhodian. Memnon was a formidable antagonist, both from his skill in war, and from his having a powerful fleet at his command, which gave him the dominion of the sea, and enabled him to threaten at will the shores of Greece and Macedonia.