At the age of twenty-two he was left by his father to defend Syria against Ptolemy the son of Lagus; he was totally defeated near Gaza (312 BC), but soon partially repaired his loss by a victory in the neighbourhood of Myus.
After an unsuccessful expedition against Babylon, and several campaigns against Ptolemy on the coasts of Cilicia and Cyprus, Demetrius sailed with a fleet of 250 ships to Athens. He freed the city from the power of Cassander and Ptolemy, expelled the garrison which had been stationed there under Demetrius of Phalerum, and besieged and took Munychia (307 BC). After these victories he was worshipped by the Athenians as a tutelary deity under the title of Soter ("Preserver").
In the campaign of 306 BC against Ptolemy he defeated Menelaus (the brother of Ptolemy) in Cyprus, and completely destroyed the naval power of Egypt. In 305 BC he endeavoured to punish the Rhodians for having deserted his cause; and his ingenuity in devising new instruments of siege, in his unsuccessful attempt to reduce the capital, gained him the appellation of Poliorcetes.
He returned a second time to Greece as liberator. But his licentiousness and extravagance made the Athenians regret the government of Cassander. He soon, however, roused the jealousy of the successors of Alexander; and Seleucus, Cassander and Lysimachus united to destroy Antigonus and his son. The hostile armies met at Ipsus in Phrygia (301 BC).
Antigonus was killed in the battle, and Demetrius, after sustaining a severe loss, retired to Ephesus. This reverse of fortune raised up many enemies against him; and the Athenians refused even to admit him into their city. But he soon afterwards ravaged the territory of Lysimachus, and effected a reconciliation with Seleucus, to whom he gave his daughter Stratonice in marriage. Athens was at this time oppressed by the tyranny of Lachares; but Demetrius, after a protracted blockade, gained possession of the city (294) and pardoned the inhabitants their former misconduct.
In the same year he established himself on the throne of Macedonia by the murder of Alexander, the son of Cassander. But here he was continually threatened by Pyrrhus, who took advantage of his occasional absence to ravage the defenceless part of his kingdom (Plutarch, Pyrrhus, 7 if.); and at length the combined forces of Pyrrhus, Ptolemy and Lysimachus, assisted by the disaffected among his own subjects, obliged him to leave Macedonia after he had sat on the throne for six years (294-288 BC).
He passed into Asia, and attacked some of the provinces of Lysimachus with varying success; but famine and pestilence destroyed the greater part of his army, and he solicited Seleucus for support and assistance. But before he reached Syria hostilities broke out; and after he had gained some advantages over his son-in-law, Demetrius was totally forsaken by his troops on the field of battle, and surrendered his person to Seleucus. His son Antigonus offered all his possessions, and even his person, in order to procure his father's liberty; but all proved unavailing, and Demetrius died in the fifty-fourth year of his age, after a confinement of three years (283). His remains were given to Antigonus, honoured with a splendid funeral at Corinth, Greece, and thence conveyed to Demetrius. His posterity remained in possession of the Macedonian throne till the time of Perseus, who was conquered by the Romans.
This entry was originally from the 1911 Encyclopedia Britannica.