（*Mardo/nios), a Persian, son of Gobryas, who was one of the seven conspirators against Smerdis the Magian, in B. C. 521. (See Hdt. 3.70, &c.)
In the spring of B. C. 492, the second year from the close of the Ionian war, Mardonius, who had recently married Artazostra, the daughter of Dareius IIystaspis, was sent by the king, with a large armament, as successor of Artaphernes, to complete the settlement of Ionia, and to punish Eretria and Athens for the aid they had given to the rebels. (Comp. Hdt. 5.99, &c.)
But while this was the nominal object of the expedition, it was intended also for the conquest of as many Grecian states as possible. Throughout the Ionian cities Mardonius deposed the tyrants whom Artaphernes had placed in power, and established democracy, -- a step remarkably opposed to the ordinary rules of Persian policy.
He then crossed the Hellespont, and, while his fleet sailed to Thasos and subdued it, he marched with his land forces through Thrace and Macedoni