The reign of Darius, the third king of Persia. (B.C. 521-485), is memorable in Grecian history. In his invasion of Scythia, his fleet, which was furnished by the Asiatic Greeks, was ordered to sail up the Danube and throw a bridge of boats across the river. The King himself, with his land forces, marched through Thrace; and, crossing the bridge, placed it under the care of the Greeks, telling them that, if he did not return within sixty days, they might break it down, and sail home. He then left them, and penetrated into the Scythian territory. The sixty days had already passed away, and there was yet no sign of the Persian army; but shortly afterwards the Greeks were astonished by the appearance of a body of Scythians, who informed them that Darius was in full retreat, pursued by the whole Scythian nation, and that his only hope of safety depended upon that bridge. They urged the Greeks to seize this opportunity of destroying the Persian army, and of recovering their own liberty, by breaking down the bridge. Their exhortations were warmly seconded by the Athenian Miltiades, the tyrant of the Thracian Chersonesus, and the future conqueror of Marathon. The other rulers of the Ionian cities were at first disposed to follow his suggestion; but as soon as Histiaeus of Miletus reminded them that their sovereignty depended upon the support of the Persian king, and that his ruin would involve their own, they changed their minds and resolved to await the Persians. After enduring great privations and sufferings Darius and his army at length reached the Danube and crossed the bridge in safety. Thus the selfishness of these Grecian despots threw away the most favourable opportunity that ever presented itself of delivering their native cities from the Persian yoke. To reward the services of Histiaeus, Darius gave him the town of Myrainus, near the Strymon. Darius, on his return to Asia, left Megabazus in Europe with an army of 80,000 men to complete the subjugation of Thrace and of the Greek cities upon the Hellespont. Megabazus not only subdued the Thracians, but crossed the Strymon, conquered the Paeonians, and penetrated as far as the frontiers of Macedonia. He then sent heralds into the latter country to demand earth and water, the customary symbols of submission. These were immediately granted by Amyntas, the reigning monarch (B.C. 510); and thus the Persian dominions were extended to the borders of Thessaly. Megabazus, on his return to Sardis, where Darius awaited him, informed the Persian monarch that Histiaeus was collecting the elements of a power which might hereafter prove formidable to the Persian sovereignty, since Myrcinus commanded the navigation of the Strymon, and consequently the commerce with the interior of Thrace. Darius, perceiving that the apprehensions of his general were not without foundation, summoned Histiaeus to his presence, and, under the pretext that he could not bear to be deprived