 He was relieved of his command by Darius, who appointed Datis and Artaphernes junior to lead the invasion of Greece in 490 BC, and though they were subsequently successful in capturing Naxos and destroying Eretria, they were later defeated at the Battle of Marathon.Mardonius came back into favour under Darius' successor Xerxes I, Mardonius' cousin and brother-in-law.Xerxes was at first not interested in renewing the war with Greece, but Mardonius, who had the most influence on Xerxes in all of Persia, repeatedly tried to convince him that he must avenge Darius' defeat.