The Anabasis of Alexander/Book V/Chapter XVI
CHAPTER XVI.
Alexander's Tactics.
Such was the arrangement which Porus made of his forces. As soon as Alexander observed that the Indians were drawn up in order of battle, he stopped his cavalry from advancing farther, so that he might take up the infantry as it kept on arriving; and even when the phalanx in quick march had effected a junction with the cavalry, he did not at once draw it out and lead it to the attack, not wishing to hand over his men exhausted with fatigue and out of breath, to the barbarians who were fresh and untired. On the contrary, he caused his infantry to rest until their strength was recruited, riding along round the lines to inspect them.[1] When he had surveyed the arrangement of the Indians, he resolved not to advance against the centre, in front of which the elephants had been posted, and in the gaps between them a dense phalanx of men; for he was alarmed at the very arrangements which Porus had made here with that express design. But as he was superior in the number
of his cavalry, he took the greater part of that force, and marched along against the left wing of the enemy for the purpose of making an attack in this direction. Against the right wing he sent Coenus with his own regiment of cavalry and that of Demetrius, with instructions to keep close behind the barbarians when they, seeing the dense mass of cavalry opposed to them, should ride out to fight them. Seleucus, Antigenes, and Tauron were ordered to lead the phalanx of infantry, but not to engage in the action until they observed[2] the enemy's cavalry and phalanx of infantry thrown into disorder by the cavalry under his own command. But when they came within range of missiles, he launched the horse-archers, 1000 in number, against the left wing of the Indians, in order to throw those of the enemy who were posted there into confusion by the incessant storm of arrows and by the charge of the horses. He himself with the Companion cavalry marched along rapidly against the left wing of the barbarians, being eager to attack them in flank while still in a state of disorder, before their cavalry could be deployed.