were eager to attack at once; but with great judgment he restrained them, gave his troops a night’s rest, and obtained time to reconnoitre completely the whole position of the enemy and the arrangement which he had made of his forces.  He then formed his own dispositions.  The army with which he was to attack above a million of men consisted of 40,300 foot and 7000 horse.  Alexander drew them up in three lines: 

The first consisted of light-armed troops, horse and foot, of good quality, which were especially intended to act against the enemy’s chariots.  The next was the main line of battle, and contained the phalanx with the rest of the heavy infantry in the centre, the heavy cavalry upon the two wings.  The third line consisted of light troops, chiefly horse, and was instructed to act against such of the Persians as should outflank the Macedonian main line and so threaten their rear.  As at Issus, Alexander took the command of the right wing himself, and assigned the left to Parmenio.

As the two armies drew near, Alexander, who found himself greatly outflanked on both wings, and saw in front of him smooth ground carefully prepared for the operations of chariots and cavalry, began a diagonal movement towards the right, which tended at once to place him beyond the levelled ground, and to bring him in contact with his enemy’s left wing rather than with his direct front.  The movement greatly disconcerted his adversary, who sought to prevent it by extending and advancing his own left, which was soon engaged with Alexander’s right in a fierce hand-to-hand conflict.  Alexander still pressed his slanting movement, and in resisting it Darius’s left became separated from his centre, while at the same time he was forced to give the signal for launching the chariots against the foe sooner than he had intended, and under circumstances that were not favorable.  The effect of the operation was much the same as at Cunaxa.  Received by the Macedonian light-armed, the chariots were mostly disabled before the enemy’s main line was reached; the drivers were dragged from the chariot-boards; and the horses were cut to pieces.  Such as escaped this fate and charged the Macedonian line, were allowed to pass through the ranks, which opened to receive them, and were then dealt with by grooms and others in the rear of the army.

No sooner had the chariot attack failed, and the space between the two lines of battle become clear, than Alexander, with the quick eye of a true general, saw his opportunity:  to resist his flank movement, the Bactrians and Sacae with the greater part of the left wing had broken off from the main Persian line, and in pressing towards the left had made a gap between their ranks and the centre.  Into this gap the Macedonian king, at the head of the “Companion” cavalry and a portion of the phalanx, plunged.  Here he found himself in the near neighborhood of Darius, whereupon he redoubled the vigor of his assault,