
Hercules And Diomedes
Prior to his adventures in Troy, Diomedes is remembered for being one of the Epigonoi, the sons of the warrior-kings who fell on the Seven Against Thebes. The Epigonoi organized a military expedition that was meant to avenge their fathers' deaths by ceding the Kingdom of Thebes. After Tydeus' death, Diomedes married an Argive woman and settled in Argos. Even as a permanent citizen of Argos, Diomedes would still spy and interfere with the affairs of his father's Calydonian homeland that was ruled by his grandfather Oeneus.
Eventually, a conspiracy was organized by a man named Thersites aiming to overthrow the King. Thersites had Oeneus put in jail and his father to the throne. Diomedes attacked and ceded the Kingdom, slaying all traitors except Thersites who managed to escape, restoring his grandfather to the throne.
Later on when Oeneus passed the Kingdom to his son-in-law Andraemon, he headed for Argos to meet Diomedes but was assassinated on the way by Thersites. Unable to find the murderers, Diomedes founded a mythical city called Oenoe at the place where his grandfather was buried to honour his death. Later during the Trojan War, Thersites was brutally slain by Achilles after having mocked at him when the latter cried over Penthesilia's dead body.