Mares of Diomedes. The Mares of Diomedes, also called the Mares of Thrace, were a herd of man-eating horses in Greek mythology.
   Magnificent, wild, and uncontrollable, they belonged to Diomedes, king of Thrace, son of Ares and Cyrene who lived on the shores of the Black Sea. Bucephalus, Alexander the Great's horse, was said to be descended from these mares.
   As the eighth of his Twelve Labours, also categorised as the second of the Non-Peloponnesian labours, Heracles was sent by King Eurystheus to steal the Mares from Diomedes. The mares' madness was attributed to their unnatural diet which consisted of the flesh of unsuspecting guests or strangers to the island.
   Some versions of the myth say that the mares also expelled fire when they breathed. The Mares, which were the terror of Thrace, were kept tethered by iron chains to a bronze manger in the now vanished city of Tirida and were named Podargos, Lampon, Xanthos and Deinos.
   Although very similar, there are slight variances in the exact details regarding the mares' capture. In one version, Heracles brought a number of volunteers to help him capture the giant horses. After overpowering Diomedes' men, Heracles broke the chains that tethered the horses and drove the mares down to sea. Unaware that the mares were man-eating and uncontrollable, Heracles left them in the charge of his favored companion, Abderus, while he left to fight Diomedes. Upon hi
Wikipedia ...