=81.= The king of Macedon wintered at Gor´dium, where he cut or untied the celebrated knot, which an ancient prophecy had declared could never be loosened except by the conqueror of Asia. With fresh reinforcements from Greece, he commenced his second campaign, in the spring of 333, by marching through Cappadocia and Cilicia to the gates of Syria. Darius met him, in the narrow plain of Issus, with an army of half a million men. Hemmed in between the mountains, the river, and the sea, the Persian horsemen could not act, and their immense numbers were rather an incumbrance than an advantage. Darius was defeated and fled across the Euphrates. His mother, wife, and children fell into the hands of the conqueror, who treated them with the utmost delicacy and respect. =82.= B. C. 333-331. The conquests of Syria, Phœnicia, and Egypt, which Alexander now accomplished in less than two years, will be described in the Macedonian history. In the spring of 331, he retraced his triumphant march through Syria, crossed the Euphrates at Thapsacus, traversed Mesopotamia, and met Darius again on the great Assyrian plain east of the Tigris. The Persian king had spent the twenty months which had intervened since the battle of Issus in mustering the entire force of his empire. The ground was carefully selected as most favorable to the movements of cavalry, and as giving him the full advantage of his superior numbers. A large space was leveled and hardened with rollers for the evolutions of the scythe-armed chariots. An important part of the infantry was formed of the brave and hardy mountaineers of Afghanistan, Bokhara, Khiva, and Thibet; and the cavalry, of the ancestors of the modern Kurds and Turcomans, a race always distinguished for bold and skillful horsemanship. A brigade of Greek auxiliaries was alone considered able to withstand the charge of Alexander’s phalanx. Altogether the forces of Darius numbered more than a million of men, and they surpassed all former general levies of the Persians in the efficient discipline which enabled them to act together as one body. =83.= The Macedonian phalanx, which formed the center of Alexander’s army, was the most effective body of heavy-armed troops known to ancient tactics. The men were placed sixteen deep, armed with the _sarissa_, or long pike, twenty-four feet in length. When set for action, the spear-heads of the first six ranks projected from the front. In receiving a charge, the shield of each man, held over the head with the left arm, overlapped that of his neighbor; so that the entire body resembled a monster clothed in the shell of a tortoise and the bristles of a porcupine. So long as it held together, the phalanx was invincible. Whether it advanced its vast weight upon an enemy like a solid wall of steel bristling with spear-points, or, kneeling, with each pike planted in the ground, awaited the attack, few dared to encounter it.