Athens: Its Rise and Fall Book III Vol II by Edward Bulwer-lytton

I. On succeeding to the throne of the East (B. C. 485), Xerxes found the mighty army collected by his father prepared to execute his designs of conquest or revenge. In the greatness of that army, in the youth of that prince, various parties beheld the instrument of interest or ambition. Mardonius, warlike and enterprising, desired the subjugation of Greece, and the command of the Persian forces. And to the nobles of the Pasargadae an expedition into Europe could not but present a dazzling prospect of spoil and power -- of satrapies as yet unexhausted of treasure -- of garrisons and troops remote from the eye of the monarch, and the domination of the capital.

The persons who had most influence over Xerxes were his uncle Artabanus, his cousin Mardonius, and a eunuch named Natacas [50]. The intrigues of the party favourable to the invasion of Europe were backed by the representations of the Grecian exiles. The family and partisans of the Pisistratidae had fixed themselves in Susa, and the Greek subtlety and spirit of enterprise maintained and confirmed, for that unprincipled and able faction, the credit they had already established at the Persian court. Onomacritus, an Athenian priest, formerly banished by Hipparchus for forging oracular predictions, was now reconciled to the Pisistratidae, and resident at Susa. Presented to the king as a soothsayer and prophet, he inflamed the ambition of Xerxes by garbled oracles of conquest and fortune, which, this time, it was not the interest of the Pisistratidae to expose.