rest of the front line of his wing fresh, and ready to take advantage of the first opportunity for striking a decisive blow. This soon came. A large body of horse, who were posted on the Persian left wing nearest to the centre, quitted their station, and rode off to help their comrades in the cavalry fight, that still was going on at the extreme right of Alexander's wing against the detachments from his second line. This made a huge gap in the Persian array, and into this space Alexander instantly charged with his guard and all the cavalry of his wing; and then pressing toward his left, he soon began to make havoc in the left flank of the Persian centre. The Shield-bearing infantry now charged also among the reeling masses of the Asiatics; and five of the brigades of the phalanx, with the irresistible might of their sarissas, bore down the Greek mercenaries of Darius, and dug their way through the Persian centre. In the early part of the battle Darius had showed skill and energy; and he now, for some time, encouraged his men, by voice and example, to keep firm. But the lances of Alexander's cavalry and the pikes of the phalanx now pressed nearer and nearer to him. His charioteer was struck down by a javelin at his side; and at last Darius's nerve failed him, and, descending from his chariot, he mounted on a fleet horse and galloped from the plain, regardless of the state of the battle in other parts of the field, where matters were going on much more favorably for his cause, and where his presence might have done much toward gaining a victory.
Alexander's operations with his right and centre had exposed his left to an immensely preponderating force of the enemy. Parmenio kept out of action as long as possible but Mazæus, who commanded the Persian right wing, advanced against him, completely outflanked him, and pressed him severely with reiterated charges by superior numbers. Seeing the distress of Parmenio's wing, Simmias, who commanded the sixth brigade of phalanx, which was next to the left wing, did not advance with the other brigades in the great charge upon the Persian centre, but kept back to cover Parmenio's troops on their right flank, as otherwise they would have been completely surrounded and cut off from the rest of the Macedonian army. By so doing, Simmias had unavoidably opened a gap in the Macedonian left centre; and a large column of Indian and Persian horse, from the Persian right centre, had galloped forward through this in-
