The legendary battle between the Persians and the Greeks, under the leadership of the Spartan King Leonidas, took place at Thermopylae in 480 BCE. The Greeks tricked the Persians, forcing them to pass through the narrows of Thermopylae, then roughly 12 meters wide, although today much wider due to the sedimentation by Sperkhios River. In doing so, the Greeks overcame the disadvantage of their small numbers, whilst also blocking an attack by the Persian cavalry. The Greeks resisted for two days. On the third day, a Greek traitor named Ephialtes, meaning nightmare, betrayed them and led the Persians along a hidden pathway to the rear of the Greeks. At that point, Leonidas released coalition forces in order for them to organize defenses further south while holding together an elite force of 300 Spartans who were committed to fighting to an honorable death.
The battle of Thermopylae was one of the most important battles in Greek and world history. Mainly from an ethical standpoint, it is a brilliant example of self-denial, self-sacrifice, and devotion to the country.