The principal achievement of the allied Grecians during this war was the burning of Sardis, the capital of the old Lydian monarchy. When Darius was informed of it he burst into a paroxysm of rage, directing his wrath chiefly against the Athenians and Euboeans who had dared to invade his dominions. "The Athenians!" he exclaimed, "who are they?" Upon being told, he took his bow and shot an arrow high into the air, saying, "Grant me, Jove, to take vengeance upon the Athenians." He also charged one of his attendants to call aloud to him thrice every day at dinner, "Sire, remember the Athenians!" As soon, therefore, as Darius had satisfied his vengeance against the Greek cities and islands of Asia, he turned his attention to the Athenians and Euboeans, in pursuance of his vow. He meditated, however, nothing less than the conquest of all Greece; but the Persian fleet that was to aid in carrying out his plans was checked in its progress, off Mount Athos, by a storm so violent that it is said to have destroyed three hundred vessels and over twenty thousand lives; and his son-in-law, Mardo'nius, who had entered Thrace and Macedon at the head of a large army, abruptly terminated his campaign and recrossed the Hellespont to Asia. * * * * * II. THE FIRST PERSIAN WAR. Darius, having renewed his preparations for the conquest of Greece, sent heralds through the Grecian cities, demanding earth and water as tokens of submission. Some of the smaller states, intimidated by his power, submitted; but Athens and Sparta haughtily rejected the demands of the Eastern monarch, and put his heralds to death with cruel mockery, throwing one into a pit and another into a well, and bidding them take thence their earth and water.