King Diomedes and King Eurystheus plotted to kill Hercules. They sent Hercules to tame Diomedes' four flesh-eating mares. While freeing the mares, Hercules and his friend Abderus were attacked by Diomedes and his army, but Hercules drowned them. When he returned, the mares had eaten Abderus. Hercules fed the mares Diomedes' body, then took them to King Eurystheus, naming the place Abdera in memory of his friend.