t. It was necessary for Alexander not only to beat
Darius, but to gain such a victory as should leave his rival without
apology and without hope of recovery.

The Persians, in fact, expected and were prepared to meet a night
attack. Such was the apprehension that Darius entertained of it that he
formed his troops at evening in order of battle, and kept them under
arms all night. The effect of this was that the morning found them jaded
and dispirited, while it brought their adversaries all fresh and
vigorous against them.

The written order of battle which Darius himself caused to be drawn up
fell into the hands of the Macedonians after the engagement, and
Aristobulus copied it into his journal. We thus possess, through Arrian,
unusually authentic information as to the composition and arrangement of
the Persian army. On the extreme left were the Bactrian, Daan, and
Arachosian cavalry. Next to these Darius placed the troops from Persia
proper, both horse and foot. Then came the Susians, and next to these
the Cadusians. These forces made up the left wing.

Darius' own station was in the centre. This was composed of the Indians,
the Carians, the Mardian archers, and the division of Persians who were
distinguished by the golden apples that formed the knobs of their
spears. Here also were stationed the bodyguard of the Persian nobility.
Besides these, there were, in the centre, formed in deep order, the
Uxian and Babylonian troops and the soldiers from the Red Sea. The
brigade of Greek mercenaries whom Darius had in his service, and who
alone were considered fit to stand the charge of the Macedonian phalanx,
was drawn up on either side of the royal chariot.

The right wing was composed of the Coelosyrians and Mesopotamians, the
Medes, the Parthians, the Sacians, the Tapurians, Hyrcanians, Albanians,
and Sacesinae. In advance of the line on the left wing were placed the
Scythian cavalry, with a thousand of the Bactrian horse and a hundred
scythe-armed chariots. The elephants and fifty scythe-armed chariots
were ranged in front of the centre; and fifty more chariots, with the
Armenian and Cappadocian cavalry, were drawn up in advance of the right
wing.

Thus arrayed, the great host of King Darius passed the night that to
many thousands of them was the last of their existence. The morning of
the first of October[50] dawned slowly to their wearied watching, and
they could hear the note of the Macedonian trumpet sounding to a