Mares of Diomedes
The Mares of Diomedes were four horses fed on human flesh, chained at bronze mangers by Diomedes, Ares's own son, who ruled Thrace's warlike Bistones. Eurystheus sent Heracles to bring them back alive as his eighth labor. Heracles overpowered their grooms, fought off Diomedes's people, fed the king to his own horses by most accounts, and delivered the tamed mares to Mycenae.
Mares of Diomedes, the man-eating horses of Thrace
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Core Myth
Apollodorus names the eighth labor as the fetching of the mares belonging to Diomedes, Ares's own son, and king of the Bistones, a warlike Thracian people. The mares were kept chained with iron at a bronze manger because of their savage temper, and fed not on grain but on the flesh of any traveler unfortunate enough to be given as a guest to their master. Heracles sailed to Thrace with a band of volunteers, overpowered the grooms guarding the mares, and drove the animals toward the sea. When the Bistones came after him in arms, Heracles left the mares in the care of his companion Abderus, a son of Hermes, while he turned to fight off the pursuers - a decision that cost Abderus his life, since the mares killed him while Heracles's attention was elsewhere. Heracles defeated the Bistones and killed Diomedes himself; several sources agree that he then fed the king's own body to the mares he had spent his reign feeding on others, a fitting reversal that also had the practical effect of calming the animals. Heracles founded the city of Abdera beside his fallen companion's grave in his memory, then brought the now-tamed mares to Eurystheus, who dedicated them to Hera rather than keeping them himself. Apollodorus adds that Eurystheus later let the mares go; freed, they made their way to Mount Olympus, where wild beasts eventually killed them - the labor's last trace of an animal that had once fed on human flesh finally ending as prey itself.
Why were the mares dangerous, and what did they actually eat?
They were fed on human flesh rather than grain. Diomedes, their owner, gave the flesh of any stranger unlucky enough to be taken in as his guest to the mares, and Apollodorus says they were chained with iron at their manger specifically because of how savage that diet had made them.
Apollodorus, Library 2.5.8
Who was Abderus, and how did he die?
Abderus was a son of Hermes and a companion of Heracles. While Heracles fought off Diomedes's people, the Bistones, he left the mares in Abderus's care, and the animals killed him in that moment of inattention. Heracles founded the city of Abdera beside his grave in his memory.
Apollodorus, Library 2.5.8
What happened to King Diomedes himself?
Heracles killed him after defeating the Bistones in battle, and most retellings agree that Diomedes's own body was then fed to the mares he had spent his reign feeding on other people's guests, a reversal that also had the effect of finally calming the animals down.
Apollodorus, Library 2.5.8
What did Eurystheus do with the mares once Heracles delivered them?
He dedicated them to Hera rather than keeping them for himself, then later released them. Freed, they wandered to Mount Olympus, where Apollodorus says wild beasts eventually destroyed them, an ending that quietly closes out an animal that had once been the predator rather than the prey.
Apollodorus, Library 2.5.8
Does every ancient source tell the labor the same way?
No. Euripides's Heracles compresses the whole episode into a single image of Heracles taming the mares with a bit at their bloody mangers, leaving out Abderus, the founding of Abdera, and Diomedes's death by his own horses entirely - a shorter version built for a chorus rather than a full narrative.
Euripides, Heracles 380-386
Later Traditions
Euripides's Heracles gives the same labor a shorter, more violent ending in its chorus's catalog of Heracles's feats: there, Heracles simply "tamed with the bit the horses of Diomedes, that greedily champed their bloody food" at their "gory mangers," without any mention of Abderus, the founding of Abdera, or Diomedes's own death feeding them, a compressed version built for a choral ode rather than a full retelling. Whether Heracles killed Diomedes by feeding him to his own mares or by some other means is itself not agreed upon across every surviving source, though the reversal of predator and prey is the detail most retellings keep.
Also Connected
3 recorded connections, each with the ancient line behind it.
Connected
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The mares belonged to Diomedes, a son of Ares and king of the warlike Thracian Bistones.
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Once tamed, Eurystheus dedicated the mares to Hera rather than keeping them for himself.
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Taming the man-eating mares of Diomedes and bringing them to Eurystheus was the eighth of Heracles's twelve labors.
Where Accounts Differ
- full narrative versus Euripides's compressed retelling
- Euripides's Heracles gives a compressed version of this labor with no mention of Abderus, the founding of Abdera, or how Diomedes died, unlike Apollodorus's fuller account.
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Mythology
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Related Terms
Sources
- Apollodorus, Library 2.5.8
- Euripides, Heracles 380-386
- Timothy Gantz, Early Greek Myth (1993)