IV. When he was about seventeen years of age, and appeared to be firmly established upon his throne, he chanced to leave the country to attend the wedding of one of the sons of Glaukias, with whom he had been brought up. The Molossians now again rose in revolt, drove out his friends, sacked the treasury, and made Neoptolemus their king. Pyrrhus having thus lost his kingdom, and being entirely destitute, fled for refuge to Demetrius, the son of Antigonus, who had married his sister Deidameia. When a young girl Deidameia had been nominally the wife of Alexander, the son of Roxana, but after the misfortunes of that family Demetrius had married her when she came of age. In the great battle of Ipsus, in which all the successors of Alexander the Great took part, Pyrrhus, while yet a youth, served with the forces of Demetrius, routed those who opposed him, and gained great distinction. He did not desert Demetrius after his defeat, but was entrusted with the care of those cities which Demetrius possessed in Greece, and kept them faithful to his cause. When he made a treaty with Ptolemy, Pyrrhus was sent to Egypt as a hostage, where he hunted and practised gymnastics with Ptolemy, showing great bodily strength and endurance. Observing that Berenike was the most powerful and intelligent of Ptolemy's wives, he paid especial court to her, and, as he knew well how to gain the favour of the powerful, though he was inclined to domineer over his inferiors, and was temperate and well-behaved, he was chosen out of many other noble youths to be the husband of Antigone, one of the daughters of Berenike, whom she bore to Philip before she married Ptolemy.