Meanwhile, Alexander had quitted Egypt, and after delaying some months in Syria while his preparations were being completed, had crossed the Euphrates at Thapsacus and marched through northern Mesopotamia along the southern flank of the Mons Masius, a district in which provisions, water, and forage were abundant, to the Tigris, which he must have reached in about lat. 36° 30’, thirty or forty miles above the site of Nineveh. No resistance was made to his advance; even the passage of the great rivers was unopposed. Arrived on the east bank of the Tigris, Alexander found himself in Assyria Proper, with the stream upon his right and the mountains of Gordyene Kurdistan at no great distance upon his left. But the plain widened as he advanced, and became, as he drew near the position of his enemy, a vast level, nowhere less than thirty miles in breadth, between the outlying ranges of hills and the 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: