As soon as Darius began to set his whole phalanx in motion, Alexander ordered Aretes to attack those who were riding completely round his right wing; and up to that time he was himself leading his men in column. But when the Persians had made a break in the front line of their army, in consequence of the cavalry sallying forth to assist those who were surrounding the right wing, Alexander wheeled round towards the gap, and forming a wedge as it were of the Companion cavalry and of the part of the phalanx which was posted here, he led them with a quick charge and loud battle-cry straight towards Darius himself. For a short time there ensued a hand-to-hand fight; but when the Macedonian cavalry, commanded by Alexander himself, pressed on vigorously, thrusting themselves against the Persians and striking their faces with their spears, and when the Macedonian phalanx in dense array and bristling[415] with long pikes had also made an attack upon them, all things at once appeared full of terror to Darius, who had already long been in a state of fear, so that he was the first to turn and flee.[416] The Persians also who were riding round the wing were seized with alarm when Aretes made a vigorous attack upon them. In this quarter indeed the Persians took to speedy flight; and the Macedonians followed up the fugitives and slaughtered them.[417] Simmias and his brigade were not yet able to start with Alexander in pursuit, but causing the phalanx to halt there, he took part in the struggle, because the left wing of the Macedonians was reported to be hard pressed. In this part of the field, their line being broken, some of the Indians and of the Persian cavalry burst through the gap towards the baggage of the Macedonians; and there the action became desperate. For the Persians fell boldly on the men, who were most of them unarmed, and never expected that any men would cut through the double phalanx and break through upon them.[418] When the Persians made this attack, the foreign prisoners also assisted them by falling upon the Macedonians in the midst of the action. But the commanders of the men who had been posted as a reserve to the first phalanx, learning what was taking place, quickly moved from the position which they had been ordered to take, and coming upon the Persians in the rear, killed many of them there collected round the baggage. But the rest of them gave way and fled. The Persians on the right wing, who had not yet become aware of the flight of Darius, rode round Alexander’s left wing and attacked Parmenio in flank.[419] CHAPTER XV. DEFEAT OF THE PERSIANS AND PURSUIT OF DARIUS.