on the land—doubtless a wise, but desperate measure. He supposed, and rightly, that after he had taken the cities on the coast, the Persian fleet would be useless, and the country would be insured to his army. (M737) Alexander found some difficulty at the siege of Halicarnassus, from the bravery of the garrison, commanded by Memnon, and the strength of the defenses, aided by the Persian fleet. But his soldiers, “protected from missiles by movable pent-houses, called tortoises, gradually filled up the deep and wide ditch round the town, so as to open a level road for his engines (rolling towers of wood) to come up close to the walls.” Then the battering-rams overthrew the towers of the city wall, and made a breach in them, so that the city was taken by assault. Memnon, forced to abandon his defenses, withdrew the garrison by sea, and Alexander entered the city. The ensuing winter months were employed in the conquest of Lydia, Pamphylia, and Pisidia, which was effected easily, since the terror of his arms led to submission wherever he appeared. At Gordium, in Phrygia, he performed the exploit familiarly known as the cutting of the Gordian knot, which was a cord so twisted and entangled, that no one could untie it. The oracle had pronounced that to the person who should untie it, the empire of Persia was destined. Alexander, after many futile attempts to disentangle the knot, in a fit of impatience, cut it with his sword, and this was accepted as the solution of the problem. (M738) Meanwhile Memnon, to whom Darius had intrusted the guardianship of the whole coast of Asia Minor, with a large Phœnician fleet and a considerable body of Grecian mercenaries, acquired the important island of Chios, and a large part of Lesbos. But in the midst of his successes, he died of sickness, and no one was left able to take his place. Had his advice been taken, Alexander could not have landed in Asia. His death was an irreparable loss to Persian cause, and with his death vanished all hope of employing the Persian force with wisdom and effect. Darius now changed his policy, and resolved to carry on offensive measures on the land. He therefore summoned a vast army, from all parts of his empire, of five hundred thousand infantry, and one hundred thousand cavalry. An eminent Athenian, Charidemus, advised the Persian king to employ his great treasure in subsidizing the Greeks, and not to dream, with his undisciplined Asiatics, to oppose the Macedonians in battle. But the advice was so unpalatable to the proud and self-reliant king, in the midst of his vast forces, that he looked upon Charidemus as a traitor, and sent him to execution.