Encyclopaedia Britannica, 11th Edition, "Armour Plates" to "Arundel, Earls of"

2. Vizier of Xerxes (Ctesias, _Pers_. 20), whom he murdered in 465 B.C.

According to Aristotle, _Pol_. v. 1311 b, he had previously killed Xerxes' son Darius, and was afraid that the father would avenge him; according to Ctesias, _Pers_. 29, Justin iii. 1, Diod. xi. 69, he killed Xerxes first and then pretended that Darius had murdered him, and instigated his brother Artaxerxes to avenge the parricide. At all events, during the first months of the reign of Artaxerxes I., he was the ruling power in the state (therefore the chronographers wrongly reckon him as king, with a reign of seven months), until Artaxerxes, having learned the truth about the murder of his father and his brother, overwhelmed and killed Artabanus and his sons in open fight.