4. Ephialtes and the Fall of Thermopylae
Ephialtes, a local Greek from Trachis, betrayed his compatriots during the Battle of Thermopylae in 480 BC by revealing a secret mountain path to the Persian king Xerxes I. This path allowed the Persians to outflank the Greek forces led by King Leonidas, leading to their defeat. Ephialtes’s name has since become synonymous with treachery in Greek culture (history.com).
