The Greeks had had four days’ rest in a fortified camp before they were drawn up in battle array, and besides this the ground between them and the Persians had been carefully reconnoitered, in order to discern if the enemy had constructed concealed pits to confuse the cavalry charge. There was no way of protecting the flanks of the army, so Alexander placed a reserve force behind with orders to move towards the right or the left, according as the expected turning movement from the Persians might develop. The Greeks moved forward on the 30th of September, with Alexander leading the Macedonian heavy cavalry and the bulk of the phalanx. He directed his attack against the enemy’s left wing, but as he did so he was charged on the flank by the Scythian and Bactrian horse. He sent against them the reserves previously mentioned, and himself engaged the Persian infantry, who had lost heart when they were attacked by the Macedonian cavalry. The manœuvers with the scythe-bearing chariots did no damage, for the Greeks made way for them to pass through their ranks, and re-formed again as soon as they had rattled past. The onslaught of the phalanx proved irresistible; the Asiatic foot could not withstand its superior armament and discipline. The Persian center was broken and again Darius had the ignominious experience of a headlong flight. The Persian cavalry, left to battle alone, was soon demoralized and could not hold its ground. Parmenio’s experience with the left wing of the Greeks was different, for he had difficulty in keeping his position against the Persian horse. He could not follow Alexander’s advance, and hence there came to be a great gap between the two positions of the army. In this open space the Persians precipitated themselves; the Greek lines in battle array were forced farther apart and their camp occupied. It was a most dangerous position, but the barbarians, instead of using their advantage, busied themselves in plundering the Greek camp. Alexander turned from pursuing the Persian center to help the hard-pressed left wing, and on his way met the enemy’s cavalry, now on their way back with the booty of the Macedonian camp. He tried to cut them off from their main body, but they fought with desperation and succeeded in breaking through. In the hand-to-hand fights one of Alexander’s closest friends, Hephæstion, was wounded.