In the last chapter but one of the preceding volume, I described the Athenian victory at Marathon, the repulse of the Persian general Datis, and the return of his armament across the Ægean to the Asiatic coast. He had been directed to conquer both Eretria and Athens: an order which he had indeed executed in part with success, as the string of Eretrian prisoners brought to Susa attested,—but which remained still unfulfilled in regard to the city principally obnoxious to Darius. Far from satiating his revenge upon Athens, the Persian monarch was compelled to listen to the tale of an ignominious defeat. His wrath against the Athenians rose to a higher pitch than ever, and he commenced vigorous preparations for a renewed attack upon them, as well as upon Greece generally. Resolved upon assembling the entire force of his empire, he directed the various satraps and sub-governors throughout all Asia to provide troops, horses, and ships, both of war and burden. For no less than three years the empire was agitated by this immense levy, which Darius determined to conduct in person against Greece.[1] Nor was his determination abated by a revolt of the Egyptians, which broke out about the time when his preparations were completed. He was on the point of undertaking simultaneously the two enterprises,—the conquest of Greece and the reconquest of Egypt,—when he was surprised by death, after a reign of thirty-six years. As a precaution previous to this intended march, he had nominated as successor Xerxes, his son by Atossa; for the ascendency of that queen insured to Xerxes the preference over his elder brother Artabazanes, son of Darius by a former wife, and born before the latter became king. The choice of the reigning monarch passed unquestioned, and Xerxes succeeded without opposition.[2] It deserves to be remarked, that though we shall meet with several acts of cruelty and atrocity perpetrated in the Persian regal family, there is nothing like that systematic fratricide which has been considered necessary to guarantee succession in Turkey and other Oriental empires. [1] Herodot. vii, 3, 4. [2] Herodot. vii, 1-4. He mentions—simply as a report, and seemingly without believing it himself—that Demaratus the exiled king of Sparta was at Susa at the moment when Darius was about to choose a successor among his sons (this cannot consist with Ktesias, Persic. c. 23): and that he suggested to Xerxes a convincing argument by which to determine the mind of his father, urging the analogy of the law of regal succession at Sparta, whereby the son of a king, born after his father became king, was preferred to an elder son born before that event. The existence of such a custom at Sparta may well be doubted.