Battle of Thermopylae
In 480 BCE, a small Greek force under the Spartan king Leonidas held the narrow coastal pass of Thermopylae against the vast army of the Persian king Xerxes I. The Greeks were ultimately defeated, but their stand delayed the invasion, bought time for other Greek forces, and became one of history's most enduring symbols of courage against overwhelming odds. The popular figure of "300 Spartans" is a simplification, since the Spartans were only part of a larger allied army.
The battle was part of the second Persian invasion of Greece. A decade earlier, Athens and its allies had helped defeat Persian forces at Marathon, and Xerxes, who inherited the throne of Darius I, set out to finish the job and punish the Greeks. He assembled a huge army and fleet. Ancient sources, especially Herodotus, give enormous numbers, but modern historians consider these exaggerated and estimate the Persian force at far fewer, though still much larger than anything the Greeks could field. Many Greek city-states were divided over whether to resist at all, and some chose to submit to Persia.
The Greeks chose Thermopylae, a narrow corridor between mountains and the sea, because it neutralized the Persian advantage in numbers. Leonidas led a force often estimated at several thousand, including his 300 Spartan hoplites, along with contingents from Thespiae, Thebes, Corinth, and other cities. At the same time, the Greek fleet fought inconclusive engagements with the Persian navy off Artemisium. According to Herodotus, the Greeks repelled frontal assaults for two days, using their heavy armor, long spears, and the constricted terrain to inflict heavy losses.
On the third day, the Persians learned of a mountain path around the pass, reportedly from a local man named Ephialtes. Realizing they would be surrounded, Leonidas dismissed most of the army. The Spartans, the Thespians, and probably some Thebans remained and fought to the end. Why Leonidas stayed is debated: it may have been to cover the retreat, to uphold Spartan honor, or in response to an oracle, as Herodotus reports.
Thermopylae did not stop the invasion. The Persians advanced and burned Athens, which had been evacuated. Yet the delay helped the Greeks prepare, and their naval victory at Salamis later in 480 BCE, followed by the land victory at Plataea in 479 BCE, ended the threat. The battle's legacy has been powerful ever since. Memorials, poems, and later retellings have cast it as a story of sacrifice for freedom, though modern historians caution that the surviving account comes largely from Greek sources, which shaped the legend from the start.