He had already during his father's lifetime distinguished himself by defeating Alexander II of Epirus at Derdia and so saving Macedonia (about 260?). On his accession he had to face a coalition which the two great leagues, usually rivals, the Aetolian and Achaean, formed against the Macedonian power. He succeeded in dealing this coalition severe blows, wresting Boeotia from their alliance. The revolution in Epirus, which substituted a republican league for the monarchy, gravely weakened his position.
Demetrius had also to defend Macedonia against the wild peoples of the north. A battle with the Dardanians turned out disastrously, and he died shortly afterwards, leaving Philip, his son by Chryseis, still a child.
Former wives of Demetrius were Stratonice, the daughter of the Seleucid king Antiochus I, Phthia the daughter of Alexander of Epirus, and Nicaea, the widow of his cousin Alexander. The chronology of these marriages is a matter of dispute.
This entry was originally from the 1911 Encyclopedia Britannica.