Ephialtes was a traitor who betrayed the Greeks by revealing a secret pass to the Persians during the Battle of Thermopylae.
In the context of ancient Greek history, Ephialtes is most famously known for his act of treachery during the Persian Wars. Specifically, his name is associated with the Battle of Thermopylae in 480 BC, where a small Greek force led by King Leonidas of Sparta held a narrow pass against the much larger Persian army of Xerxes I.
According to the historian Herodotus, Ephialtes, a local Greek from the region of Malis, sought to gain a reward from Xerxes by informing him of a mountain path around the pass of Thermopylae. This path would allow the Persians to outflank the Greek forces, who were defending the pass to delay the Persian advance into Greece.
The Greek forces at Thermopylae, comprised of approximately 300 Spartans and their allies, had successfully held off the Persians for two days. However, after learning of the secret path from Ephialtes, the Persians were able to send a detachment around the pass, thus surrounding the Greeks.
Faced with encirclement, Leonidas dismissed the bulk of the Greek army, remaining behind with a small contingent of Spartans and other Greek volunteers to make a last stand. This heroic action allowed the other Greek forces to retreat and regroup. The Spartans and their allies fought to the death, and their sacrifice became a symbol of courage and resistance against overwhelming odds.
Ephialtes’ betrayal had a significant impact on the course of the battle, and his name has since become synonymous with treachery in Western culture. The exact fate of Ephialtes after the battle is not well-documented, but some accounts suggest that he was eventually killed, possibly as retribution for his betrayal.