Hercules and the Mares of Diomedes

At a Glance

Central figures: Hercules, the half-mortal son of Jupiter, performing the eighth of his twelve labors; Diomedes, king of the Bistones in Thrace, who fed his horses on human flesh; and Abderus, Hercules’s young companion.
Setting: Thrace, the wild country north of Greece, and the coastal settlement that would become Abdera; the labor is recounted in Roman tradition through references in Hyginus’s Fabulae and later Roman mythographers.
The turn: Hercules captured the four mares and entrusted them briefly to Abderus, who was dragged down and killed by the animals before Hercules could return.
The outcome: Hercules killed Diomedes and fed the king’s body to his own mares, which calmed them enough to be led back to Eurystheus in Mycenae, who released them into the wild.
The legacy: Hercules founded the city of Abdera in Thrace at the site where Abderus fell, naming it for his dead companion - a city that endured for centuries as a Greek and later Roman settlement.

The mares did not look wrong. That was the problem. They were beautiful animals - tall, muscled, glossy-coated, with the deep chests and clean legs of horses bred for war. Visitors to the court of Diomedes sometimes admired them before they understood what hung in strips from the bronze manger posts, or why the stable floors were stained in ways that hay and mud could not explain.

Diomedes, king of the Bistones, kept four mares. Their names were Podargos, Lampon, Xanthos, and Deinos. He fed them on the flesh of strangers.

The Eighth Labor

Eurystheus, who set the labors and chose each one for its likelihood of killing Hercules, had heard reports from Thrace. Traders who survived the Bistonian coast spoke of horses that screamed like women and a king who chained guests to the feeding troughs at nightfall. Eurystheus sent Hercules north.

Hercules did not go alone. With him traveled a small company, among them a young man named Abderus. The sources disagree on who Abderus was - some call him a son of Mercury, others simply a friend, a companion from Opus in Locris who had followed Hercules out of loyalty or ambition or both. He was young. That much every account preserves.

The journey into Thrace took them through country that grew wilder as they moved. The Bistones were not a settled, civic people. They lived in hill-forts, worshipped Mars in his rawest aspect - not the father of Romulus, not the guardian of Roman fields, but the older thing, the god of slaughter and blood-frenzy. Diomedes ruled them as a war-chief rules, by violence sustained and violence promised.

The Stable Yard

Hercules reached the palace - if it could be called that - near the shore. He did not present himself as a guest. The stories of what happened to guests had traveled far enough. He came at night, or at dawn, or during the confusion of a feast, depending on which version one follows. The essential action is the same in all of them: he went straight for the stable.

The four mares were chained to their mangers with iron. The chains were heavy, the kind used for anchoring ships, not for tethering horses. The mangers themselves were bronze, bolted to stone. Hercules broke the chains. Some accounts say he broke the manger-posts too, tearing the bronze fixtures from the stable wall with his hands.

The mares, freed, did not bolt. They turned toward him. They were not afraid of men. Men were food. Hercules drove them out of the stable and down toward the shore, where his companions waited with a boat. He needed to get the animals to open ground, away from the palace, before the Bistones mustered. But the mares fought him - not with the panic of frightened horses but with the focused aggression of predators. They bit. They lunged. They reared and struck with their front hooves, aiming for his head and chest.

Hercules could handle them - he was Hercules - but he could not both hold them and fight whatever force Diomedes was gathering behind him. So he handed the lead-chains to Abderus.

Abderus

It was a task of minutes. Hold them here on the beach. I will deal with the king and come back. Abderus took the chains. He was strong enough for ordinary horses.

These were not ordinary horses.

What happened next happened fast. The mares pulled Abderus off his feet. He held on - perhaps he thought letting go would be worse, that loose man-eating horses on an open beach would be harder to recover than restrained ones. They dragged him across the sand and the rocks. They turned on him. By the time Hercules came back from the fight at the palace, Abderus was dead. The mares had fed.

The sources do not dwell on the details of the body. They note that Hercules found what remained and understood what had happened. He did not rage in the way the poets sometimes describe - tearing his hair, crying out to Jupiter. He was quiet. He had work to do.

Diomedes at the Manger

Hercules had already broken the Bistonian counterattack. Some versions say he diverted a river to flood the plain behind the palace, scattering Diomedes’s warriors. Others say he simply fought through them. Either way, he had Diomedes. The king was alive, captured, disarmed.

Hercules brought Diomedes to the mares.

The symmetry was deliberate. A king who fed strangers to his horses would himself be fed to them. Hercules threw Diomedes into the enclosure where the mares now stood, still red-mouthed, still restless. They ate their master. And here the accounts note something strange: after consuming Diomedes, the mares calmed. The frenzy went out of them. They stood with their heads low, breathing hard, and allowed themselves to be led.

Whether this was because the flesh of their own keeper broke whatever spell or habit drove them, or simply because they were finally sated, no source explains. The result was practical. Hercules bound their mouths, roped them together, and drove them south.

The Founding of Abdera

Before he left Thrace, Hercules buried Abderus - or what could be gathered of him - near the shore where he had fallen. He raised a mound over the grave. And beside the mound, he marked the site for a city. He called it Abdera.

The city was real. It stood on the Thracian coast, a port that traded in grain and timber, that produced the philosopher Democritus and the sophist Protagoras. Romans knew it. It persisted through the centuries, passed from Thracian to Greek to Macedonian to Roman hands. The name never changed. Whether its inhabitants remembered why it bore a dead boy’s name is another question.

The Mares Released

Hercules drove the four mares south to Mycenae and presented them to Eurystheus as proof of the labor completed. Eurystheus - who lived behind walls and received Hercules’s trophies through intermediaries, because he was afraid of the man he kept sending to die - did not want the horses. He could not stable them. He could not ride them. He could not sell man-eating mares in any market.

He released them into the hills around Mycenae. The mares scattered into the wild country, and later writers claimed their bloodline ran through the horses of the region for generations, though no subsequent horse in the line ate human flesh. The madness had ended with Diomedes.

Hercules moved on. The ninth labor waited. Abdera stood on its shore, a city built on a grave, named for the one loss Hercules could not undo by strength.