The war, thus commenced between Athens and AEgina, went on for a long time, increasing in bitterness and cruelty as the injuries increased in number and magnitude which the belligerent parties inflicted on each other. Such was the state of things in Greece when Darius organized his great expedition for the invasion of the country. He assembled an immense armament, though he did not go forth himself to command it. He placed the whole force under the charge of a Persian general named Datis. A considerable part of the army which Datis was to command was raised in Persia; but orders had been sent on that large accessions to the army, consisting of cavalry, foot soldiers, ships, and seamen, and every other species of military force, should be raised in all the provinces of Asia Minor, and be ready to join it at various places of rendezvous. Darius commenced his march at Susa with the troops which had been collected there, and proceeded westward till he reached the Mediterranean at Cilicia, which is at the northeast corner of that sea. Here large re-enforcements joined him; and there was also assembled at this point an immense fleet of galleys, which had been provided to convey the troops to the Grecian seas. The troops embarked, and the fleet advanced along the southern shores of Asia Minor to the AEgean Sea, where they turned to the northward toward the island of Samos, which had been appointed as a rendezvous. At Samos they were joined by still greater numbers coming from Ionia, and the various provinces and islands on that coast that were already under the Persian dominion. When they were ready for their final departure, the immense fleet, probably one of the greatest and most powerful which had then ever been assembled, set sail, and steered their course to the northwest, among the islands of the AEgean Sea. As they moved slowly on, they stopped to take possession of such islands as came in their way. The islanders, in some cases, submitted to them without a struggle. In others, they made vigorous but perfectly futile attempts to resist. In others still, the terrified inhabitants abandoned their homes, and fled in dismay to the fastnesses of the mountains. The Persians destroyed the cities and towns whose inhabitants they could not conquer, and took the children from the most influential families of the islands which they did subdue, as hostages to hold their parents to their promises when their conquerors should have gone. [Illustration: THE INVASION OF GREECE.] The mighty fleet advanced thus, by slow degrees, from conquest to conquest, toward the Athenian shores. The vast multitude of galleys covered the whole surface of the water, and as they advanced, propelled each by a triple row of oars, they exhibited to the fugitives who had gained the summits of the mountains the appearance of an immense swarm of insects, creeping, by an almost imperceptible advance, over the smooth expanse of the sea.