(Μαρδόνιος), 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 Macedonia, reducing on his way the tribes which had not yet submitted to Persia. But the fleet was overtaken by a storm off Mount Athos, in which it was said that 300 ships and 20,000 men were lost; and Mardonius himself, on his passage through Macedonia, was attacked at night by the Brygians, a Thracian tribe, who slaughtered a great portion of his army. He remained in the country till he had reduced them to submission; but his force was so weakened by these successive disasters, that he was obliged to return to Asia. His failure was visited with the displeasure of the king, and he was superseded in the command by Datis and Artaphernes, B. C. 490. On the accession of Xerxes, in B. C. 485, Mardonius, who was high in his favour, and was connected with him by blood as well as by marriage, was one of the chief instigators of the expedition against Greece, with the government of which he hoped to be invested after its conquest; and he was appointed one of the generals of the whole land army, with the exception of the thousand Immortals, whom Hydarnes led. After the battle of Salamis (B. C. 480), he became alarmed for the consequences of the advice he had given, and persuaded Xerxes to return home with the rest of the army, leaving 300,000 men under his command for the subjugation of Greece. Having wintered in Thessaly, he resolved, before commencing operations, to consult the several Grecian oracles, for which purpose he employed a man of the name of Mys, a native of Europus in Caria. Herodotus professes his ignorance of the answers returned, but he connects with them the step which Mardonius immediately afterwards took, of sending Alexander I., king of Macedonia, to the Athenians, whose πρόξενος he was, with a proposal of very advantageous terms if they would withdraw themselves from the Greek confederacy. The proposal was rejected, and Mardonius poured his army into Attica and occupied Athens without resistance, the Athenians having fled for refuge to Salamis. Thither he sent Murychides, a Hellespontine Greek, with the same proposal he had already made through Alexander, but with no better success than before. From Attica (a country unfavourable for the operations of cavalry, and full of narrow defiles, through which retreat would be dangerous if he were defeated) he determined to fall back on Boeotia as soon as he heard that the Spartans under Pausanias were on their march against him. But before his departure he reduced Athens to ruins, having previously abstained from damaging the city of the country as long as there had been any hope of winning over the Athenians. On his retreat from Attica he received intelligence that a body of 1000 Lacedaemonians had advanced before the rest into Megara, and thither accordingly he directed his march with the view of surprising them, and overran the Megarian plain,--the furthest point towards the west, according to Herodotus, which the Persian army ever reached. Hearing, however, that the Greek force was collected at the Isthmus of Corinth, he passed eastward through Deceleia, crossed Mount Parnes, and, descending into Boeotia, encamped in a strong position on the southern bank of the Asopus. The Greeks arrived not long after at Erythrae and stationed themselves along the skirts of Mount Cithaeron. Mardonius waited with impatience, expecting that they would descend into the plain and give him battle, and at length sent his cavalry against them under MARSISTIUSs. After their success over the latter the Greeks removed further to the west near Plataea, where they would have a better supply of water, and hither Mardonius followed them. The two armies were now stationed on opposite banks of a tributary of the Asopus, which Herodotus calls by the name of the main stream. After waiting ten days, during which the enemy's force was receiving continual additions, Mardonius determined on an engagement in spite of the warnings of the soothsayers and the advice of Artabazus, who recommended him to fall back on Thebes, where plenty of provisions had been collected, and t try the effect of Persian gold on the chief men in the several Grecian states; and his resolution of fighting was further confirmed when, the Persian cavalry having taken and choked up the spring on which the Greeks depended for water, lPasanias again decamped and moved with his forces still nearer to Plataea. Mardonius then crossed the river and pursued him. In the battle of Plataea which ensued (September, B. C. 479), he fought bravely in the front of danger with 1000 picked Persians about him, but was slain by Aeimnestus or Arimnestus, a Spartan, and his fall was the signal for a general rout of the barbarians. (Hdt. 6.43-45, 94, 7.5, 9, 82, 8.100, &100.113, &100.133-144, 9.1-4, 12-15, 38-65 ; Plut. Arist. 10_19; Diod. 11.1, 28_31; Just. 2.13, 14; Strab. ix. p.412; C. Nep. Paus. 1.)