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's 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 knobs of their spears. Here also were stationed the body-guard 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 were alone considered fit to stand in 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, two thousand one hundred and eighty-two years ago, dawned slowly to their wearied watching, and they could hear the note of the Macedonian trumpet sounding to arms, and could see King Alexander's forces descend from their tents on the heights, and form in order of battle on the plain. [See Clinton's "Fasti Hellenici." The battle was fought eleven days after an eclipse of the moon, which gives the means of fixing the precise date.]