Heracles wrestling the Mares of Diomedes.

Heracles and the Mares of Diomedes: Greek Hero VS Man-Eating Beasts

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By now, you’re probably aware that the Greek hero Heracles (a.k.a. Hercules) had to complete twelve arduous labors as retribution for killing his wife and kids in a divinely-induced rage. The eighth of these involved tackling some man-eating horses that wanted to take a bite out of pretty much everyone.

Diomedes’ Fearsome Horses

Pseudo-Apollodorus recounts in his Library that these mares belonged to King Diomedes of the Bistones tribe, “a very war-like Thracian people.” Thrace, a region that included the northeastern part of modern Greece, southeastern Bulgaria, and a bit of western Turkey, was seen by the ancient Greeks as a wild place, home of vicious barbarians. Martial Diomedes, lord of the Bistones, was aptly a son of the god of war, Ares, and Cyrene, but he was best-known for owning man-eating mares.

In order to catch these mares, Heracles and some of his friends decided to sail to Thrace. Strabo says that when he got to Thrace, Heracles didn’t have enough horses to get across a plain that was below the sea level, so he dug a canal, flooded the plain, and got the best of his enemies. Clever! To get the horses alone, he then tossed the mares’ grooms into the sea.

Hercules and the Mares of Diomedes. Detail of The Twelve Labours Roman Mosaic from Llíria (Valencia, Spain).

Hercules and the Mares of Diomedes. Detail of The Twelve Labours Roman Mosaic from Llíria (Valencia, Spain). ( CC BY-SA 3.0 )

According to Diodorus Siculus, the “feeding-troughs of these horses were of brass because the steeds were so savage, and they were fastened by iron chains because of their strength, and the food they ate was not the natural produce of the soil but they tore apart the limbs of strangers and so got their food from the ill lot of hapless men.” The Bistones attacked the invaders, so Heracles put his pal Abderus—a son of the god Hermes—in charge of the horses. Bad idea: The mares took off and either dragged Abderus to his death or ate him.

Conclusion of the Tale

What happened next depends on the version of the story you read. Pseudo-Apollodorus says Heracles just killed Diomedes, caused the Bistones to flee, and founded a city named Abdera near the spot where his pal/possible lover had died. Diodorus, however, offers the more popular account, that Heracles fed Diomedes to his own mares. Irony at its finest! Once the mares were done munching on their former master, they reverted to regular horses. Divine order—which Diomedes had violated by teaching the horses to eat humans—had been restored!

Diomedes Devoured by his Horses - Gustave Moreau (1866).

Diomedes Devoured by his Horses - Gustave Moreau (1866). ( Public Domain )

Heracles took the mares, now domesticated, back to his cousin, Eurystheus, to whom he was beholden during the time of his labors. Diodorus claims Eurystheus dedicated them to the goddess Hera, and the mares’ descendants were alive through the time of Alexander the Great.

Pseudo-Apollodorus opines that Eurystheus actually set the horses free, and they galloped off to Mount Olympus, where wild animals ate them up. In Seneca the Younger’s play Agamemnon, the chorus of Greek women recalls the many great heroes of the city of Argos, chief amongst whom was Heracles; of Diomedes’s mares, they quip ironically, “Cruel, he offered his savage horses the gore of strangers – and the blood of their driver was the last to stain red their jaws.”

Top Image: Heracles wrestling the Mares of Diomedes. Source: spinningwebbs.com

By Carly Silver


Apollodorus. The Library . Translated by Sir James George Frazer. New York: G.P. Putnam’s Sons, 1921.

Rabadjiev, Kostadin. “Religion .” A Companion to Ancient Thrace . Edited by Julia Valeva, Emil Nankov, and Denver Graninger. Malden, MA: John Wiley and Sons, 2015. 443-456.

Sears, Matthew A. Athens, Thrace, and the Shaping of Athenian Leadership. New York: Cambridge University Press, 2013.

Seneca, Lucius Annaeus. “Agamemnon.” Seneca’s Tragedies . Volume 2.  Translated by Frank Justus Miller. New York: G.P. Putnam and Sons, 1917.

Siculus, Diodorus. The Library of History . Volume 2. Translated by C.H. Oldfather. Cambridge, MA: Harvard University Press, 1935.

Spartacus and the Slave Wars: A Brief History With Documents. Translated by Brent D. Shaw. New York: Palgrave McMillan, 2001.

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