Diomedes was the son of Ares, the god of war, and the king of the Bistones, a Thracian tribe of warlike people. While travelling in connection with this Labor, Herakles visited King Admetos. His wife Alcestis had just died. Herakles wrestled Death for Alcestis and he won. Alcestis was returned to life. This event is the basis for Euripides' play "Alcestis". Eurystheus dedicated the savage horses to Hera. They were said to have bred into the age of Alexander the Great. 