great
river. Darius, whose headquarters had been at Arbela, south of the Zab,
on learning Alexander's approach, had crossed that stream and taken post
on the prepared ground to the north, in the neighborhood of a small town
or village called Gaugamela. Here he drew up his forces in the order
which he thought best, placing the scythed chariots in front, with
supports of horse--Scythian, Bactrian, Armenian, and Cappadocian--near
to them; then, the main line of battle, divided into a centre and two
wings, and composed of horse and foot intermixed; and finally a reserve
of Babylonians. Sitaceni, and others, massed in heavy column in the
rear. His own post was, according to invariable Persian custom, in
the centre; and about him were grouped the best troops--the Household
brigade, the Melophori or Persian foot-guards, the Mardian archers, some
Albanians and Carians, the entire body of Greek mercenaries, and the
Indians with their elephants.

Alexander, on his side, determined to leave nothing to chance. Advancing
leisurely, resting his troops at intervals, carefully feeling his way by
means of scouts, and gradually learning from the prisoners whom he
took, and the deserters who came over to him, all the dispositions and
preparations of the enemy, he arrived opposite the position of Darius on
the ninth day after his passage of the Tigris. His officers 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