=37.= B. C. 490. A second great expedition, two years later, was conducted by Datis, accompanied by Artaphernes, son of the former satrap of that name, and nephew of the king. Having passed the sea, they fell first upon Eretria, which was taken by treachery, its temples burnt, and its inhabitants bound in chains for transportation to Asia. The first decisive trial of strength between Persia and the western Greeks took place at Mar´athon, in Attica. The Persians numbered 100,000 men, the Greeks but little more than 10,000. The Medo-Persian troops had hitherto been considered invincible; but that magnificent soldiery was now, to a certain extent, replaced by unwilling conscripts from conquered tribes, who marched, dug, or fought under the lash of overseers. Miltiades, who, as prince of the Chersonesus, had served in the Persian armies, well knew this element of weakness, and it was with just confidence in the superiority of his free Athenians that he gave orders for the battle. =38.= In the center, where the native Persians fought, they gained the advantage, and pursued the Athenians up one or two of the valleys which surround the base of Mount Kotro´ni; but, at the same time, both the right and left of the Asiatics were defeated by the Greeks, who, instead of pursuing, united their forces on the field to the relief of their center, and thus gained a complete victory. The Persians fled to their ships, now fiercely followed by the Greeks, and a still more furious contest ensued at the water’s edge. The Athenians sought to fire the fleet, but seven galleys only were destroyed; the rest, with the shattered remains of the army, made good their escape. =39.= The Persian commander did not lose his spirit in defeat. Encouraged by a preconcerted signal of the partisans of Hip´pias, he sailed immediately around Attica, hoping to surprise Athens in the absence of its defenders. But Miltiades, too, had seen the glittering shield raised upon a mountain-top, and guessed its meaning. Leaving Aristi´des with one tribe to guard the spoils of the battle-field, he led his army by a rapid night-march across the country to Athens. When Datis, the next morning, having doubled the point of Su´nium, sailed up the Athenian harbor, he saw upon the heights above the city the same victorious troops from whom his men had fled the evening before. He made no attempt to land, but sailed away with his Eretrian prisoners to the coasts of Asia. [Illustration: Silver Daric of Darius I, enlarged one-half.] =40.= Rather angered than dismayed by these failures, Darius prepared to lead in person a still greater expedition against the Greeks. But a revolt in Egypt first diverted his attention, and his death, in the following year, gave the free states of Europe time to complete their preparations for defense. B. C. 486.