Apollodorus Library 1.8.6

[6] But the sons of Agrius, to wit, Thersites, Onchestus, Prothous, Celeutor, Lycopeus, Melanippus, wrested the kingdom from Oeneus and gave it to their father, and more than that they imprisoned Oeneus in his lifetime and tormented him. ¹ Nevertheless Diomedes afterwards came secretly with Alcmaeon from Argos and put to death all the sons of Agrius, except Onchestus and Thersites, who had fled betimes to Peloponnese; and as Oeneus was old, Diomedes gave the kingdom to Andraemon who had married the daughter of Oeneus, but Oeneus himself he took with him to Peloponnese. Howbeit, the sons of Agrius, who had made their escape, lay in wait for the old man at the hearth of Telephus in Arcadia, and killed him. But Diomedes conveyed the corpse to Argos and buried him in the place where now a city is called Oenoe after him. ² And having married Aegialia, daughter of Adrastus or, as some say, of Aegialeus, he went to the wars against Thebes and Troy.