 He was assassinated on the way (in Arcadia) by Thersites and Onchestus.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, Thersites fought against the Trojans in the Trojan War and noble Diomedes did not mistreat him (however, Thersites was hated by all the other Achaeans).