Some of them, however, were anything but eager to take part. Achilles and Ulysses, the two most important in the subsequent war, endeavored to escape this necessity. Achilles was the son of the sea-nymph Thetis, who had dipped him when an infant in the river Styx, the waters of which magic stream rendered him invulnerable to any weapon except in one spot,--the heel by which his mother had held him. But her love for her son made her anxious to guard him against every danger, and when the chieftains came to seek his aid in the expedition, she concealed him, dressed as a girl, among the maidens of the court. But the crafty Ulysses, who accompanied them, soon exposed this trick. Disguised as a pedler, he spread his goods, a shield and a spear among them, before the maidens. Then an alarm of danger being sounded, the girls fled in affright, but the disguised youth, with impulsive valor, seized the weapons and prepared to defend himself. His identity was thus revealed. Ulysses himself, one of the wisest and shrewdest of men, had also sought to escape the dangerous expedition. To do so he feigned madness, and when the messenger chiefs came to seek him they found him attempting to plough with an ox and a horse yoked together, while he sowed the field with salt. One of them, however, took Telemachus, the young son of Ulysses, and laid him in the furrow before the plough. Ulysses turned the plough aside, and thus showed that there was more method than madness in his mind. And thus, in time, a great force of men and a great fleet of ships were gathered, there being in all eleven hundred and eighty-six ships and more than one hundred thousand men. The kings and chieftains of Greece led their followers from all parts of the land to Aulis, in Boeotia, whence they were to set sail for the opposite coast of Asia Minor, on which stood the city of Troy. Agamemnon, who brought one hundred ships, was chosen leader of the army, which included all the heroes of the age, among them the distinguished warriors Ajax and Diomedes, the wise old Nestor, and many others of valor and fame. The fleet at length set sail; but Troy was not easily reached. The leaders of the army did not even know where Troy was, and landed in the wrong locality, where they had a battle with the people. Embarking again, they were driven by a storm back to Greece. Adverse winds now kept them at Aulis until Agamemnon appeased the hostile gods by sacrificing to them his daughter Iphigenia,--one of the ways which those old heathens had of obtaining fair weather. Then the winds changed, and the fleet made its way to the island of Tenedos, in the vicinity of Troy. From here Ulysses and Menelaus were sent to that city as envoys to demand a return of Helen and the stolen property.