Battle of Thermopylae

Setting the scene

By 480 BCE, Persian King Xerxes I sought revenge for Marathon and to conquer Greece. He assembled a massive invasion force—ancient sources claim millions, modern estimates suggest 200,000-300,000 troops and 1,200 ships. The Persians crossed the Hellespont on pontoon bridges and marched through Thrace. Greek city-states, led by Athens and Sparta, formed a defensive alliance. The Greeks decided to block the Persians at Thermopylae, a narrow coastal pass in central Greece that negated Persian numerical advantage.

What happened

In August 480 BCE, King Leonidas of Sparta led a Greek force of about 7,000 men, including 300 Spartans, to Thermopylae. For two days, the Greeks held the pass, with hoplites in phalanx formation slaughtering Persians in the narrow space. On the third day, a Greek traitor named Ephialtes showed the Persians a mountain path around the pass. Leonidas dismissed most allies but stayed with his 300 Spartans, 700 Thespians, and 400 Thebans to cover the retreat. They fought to the death, with Leonidas killed and the survivors overwhelmed after their spears broke.

Why it still matters

The Battle of Thermopylae was a Persian tactical victory but a Greek strategic and moral triumph. The heroic last stand bought time for the Greek navy to prepare and inspired Greek resistance. Thermopylae became the ultimate symbol of courage against overwhelming odds, sacrifice for freedom, and Spartan military virtue. The battle demonstrated the effectiveness of terrain and heavy infantry, and the power of a heroic defeat to inspire a nation. Though the Persians went on to sack Athens, they were defeated at Salamis and Plataea. Thermopylae's legend, amplified by Herodotus and later popular culture, remains one of history's most famous last stands.

Background

The Battle of Thermopylae was fought in 480 BC at Thermopylae between the Achaemenid Persian Empire under Xerxes and an alliance of Greek city-states led by Sparta under Leonidas I. Lasting over the course of three days, it was one of the most prominent battles of both the second Persian invasion of Greece and the wider Greco-Persian Wars. The stand became legendary despite the Greek defeat there. Even centuries later, this episode remains a reference point for how empires rise, fracture, and transform.