Alexander won this decisive battle at Gaugamela (331) by using his phalanx with great effect in restraining the charges of the enemy, while with his cavalry he penetrated the Barbarian lines. He particularly directed his charge against the position of Darius himself, well knowing, after an experience at the earlier battle of Issus, that if once their king were put to flight, the Persians would become demoralized.
[Darius drew up his men, stationing himself with his picked Persians in the center, on either side a host of Greek mercenaries and Indian auxiliaries. Strengthening the center were many Babylonians. On the left wing besides the masses of Asiatic hordesmen were 100 scythe-bearing chariots; on the right the Medes, Sacse, and many other brave tribal contingents. The Barbarian host far outflanked the inferior numbers of Alexander. Alexander posted on his left the confederate Greeks and the Thessalian cavalry under Parmenio, in the center his phalanx, to the right his hypaspists (semi-light infantry) and his ” Companion ” Macedonian cavalry, his best corps. Covering the flanks to guard against a rear attack were some special divisions of cavalry, archers, and javelin men.]
How the Battle Opened
When the armies drew near each other, Darius and the men especially around him were observed opposite Alexander himself and his royal squadron of cavalry. Alexander led his own army more towards the right, and the Persians marched parallel along with him, far outflanking him upon their left. Then the Scythian cavalry rode along the line and came into conflict with the front men of Alexander’s army; nevertheless he still continued to march towards the right, and almost entirely got beyond the ground that had been cleared and leveled by the Persians. Then Darius, fearing that his chariots would become useless if the Macedonians advanced upon the uneven ground, ordered the front ranks of his left wing to ride round the right wing of the Macedonians, where Alexander was commanding, to prevent him from marching his wing any further.
[This led to countermoves by Alexander and precipitated a general cavalry engagement; the Greeks suffered severely, but sustained the assaults, and] assailing the enemy violently squadron by squadron, succeeded in pushing them out of rank. Meanwhile the Barbarians launched the scythed-chariots against Alexander himself, to throw his phalanx into confusion; but in this they were grievously deceived. For as soon as they approached the [Macedonian] javelin men, who had been posted in front of the “Companion” cavalry, hurled their darts at some of the horses; others they seized by the reins and pulled the drivers off, and standing round the horses killed them. Yet some got right through the ranks; for the men stood apart, and opened their ranks, as they had been taught, wherever the chariots attacked. Thus commonly the chariots went through safely, and their drivers were unhurt, but the [rear guard] later overpowered them.
Alexander charges Himself
As soon as Darius set his whole battle line in motion, Alexander ordered Aretes to attack those who were riding clear around his right wing; and up to that time he was himself leading his men in column. But when the Persians made a break in the front line of their army, when their cavalry charged to aid those executing the flanking movement, Alexander wheeled 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 a loud battle cry straight towards Darius. Then came a short hand-to-hand melee; but when the Macedonian horse, led 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, bristling with long pikes, had joined in the attack, general terror smote Darius, whose courage already had been shaken; so that he was the first to turn and flee. Likewise the Persians who were trying to outflank, panic-stricken at the vigorous attack of Aretes, took to flight; and in this quarter the Macedonians chased after and slaughtered the fugitives.
The Final Rout of the Asiatics
[Elsewhere on the battle field, however, the Persians pressed boldly; broke through the Macedonian line and began to plunder Alexander’s camp; while others attacked Parmenio’s division on the flank, putting it in great straits. At the news of Parmenio’s peril] Alexander turned back from the pursuit, and wheeling round with the “Companion” cavalry led them at full speed against the Barbarians’ right wing. Here ensued the most obstinately contested cavalry fight in the whole battle. For drawn up by squadrons, the foreigners wheeled round in deep column, and falling on Alexander’s men face to face, no longer relied on javelin casting, or skillful deploying of horses, as is usual in cavalry battles, but every man for himself strove desperately to break through what stood in his way, as his only means of safety. Here about 60 of Alexander’s “Companions” fell [and several leaders] were wounded. But these foes, too, Alexander overcame; and such as could force their way through his ranks fled with all their might.
Meantime [ere Alexander could come to their help] the Thessalian cavalry [under Parmenio] in a splendid struggle were not falling short of Alexander’s own success in the combat. For the Barbarians on the right wing were already beginning to fly when he came on the scene of [this] conflict; so that again he wheeled, and started in pursuit of Darius once more, keeping up the chase while daylight lasted. [After resting his men till midnight, Alexander pursued again all next day, but did not take the king, for] Darius went on fleeing without any rest. However, the money and all his other wealth were captured, likewise his chariot; and his spear and bow were also taken, as they had been after Issus. Of Alexander’s men about 100 were killed and more than 1000 of his horses; either from wounds or exhausted in the pursuit. . . . Of the Barbarians there are said to have been 300,000 slain, and far more taken prisoner than were killed.