Deiphontes was a hero of the Heraclid line, a son of Antimachus descended from Ctesippus, the son of Heracles. He married Hyrnetho, the favourite daughter of Temenus the Heraclid, and by her became the father of Antimenes, Xanthippus, Argeius, and a daughter, Orsobia. Temenus relied on Deiphontes as his general and adviser and favoured him over his own sons; their jealousy led them to murder their father. In the disputed aftermath Deiphontes settled at Epidaurus, where Hyrnetho's brothers contrived her death and Deiphontes founded a sanctuary in her honour.
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I.Family
Deiphontes was a son of Antimachus and was descended from Ctesippus, the son of Heracles by Deianira, marking him as a member of the Heraclid line.
He married Hyrnetho, the daughter of Temenus the Heraclid, and by her became the father of three sons, Antimenes, Xanthippus, and Argeius, and a daughter, Orsobia.
II.Reign
When Temenus obtained Argos as his share in the division of the Peloponnese, he bestowed his affections on his daughter Hyrnetho and her husband Deiphontes, employing Deiphontes as his general and chief adviser. Temenus's sons, fearing that he meant to make Deiphontes his successor, are said to have plotted against their father and had him murdered. According to the Bibliotheca, after the death of Temenus the army, abhorring the parricides, declared Deiphontes and Hyrnetho his rightful successors.
Pausanias, however, reports a different story. By his account it was not Deiphontes who succeeded after Temenus's death but Ceisus, while Deiphontes went to live at Epidaurus together with the army that was attached to him, and from there expelled the Ionian king Pityreus. His brothers-in-law, who begrudged him possession of their sister Hyrnetho, came to Epidaurus and tried to persuade her to leave her husband; when this failed, they carried her off by force. Deiphontes pursued them, killed one of them, Cerynes, and then grappled with the other, Phalces, who held Hyrnetho in his arms. In the struggle Hyrnetho was unintentionally killed by her own brother, who escaped, and Deiphontes carried her body back to Epidaurus, where he erected a sanctuary to her.
III.Decline and end of monarchy at Argos
From this time the royal prerogative at Argos began to lose ground quickly. Ceisus (or Cisus) was succeeded by Lacidamus, who had little more than the title of king.
His son Meltas, impatient of such restraint, tried too late to restore the monarchy to its ancient dignity. But the people had by then grown so powerful that, on discovering his design, they put an effectual stop to it and ended kingly power altogether, reducing the government to a democracy and condemning the prince to death.