The pass at Thermopylae — the Hot Gates, named for the sulphurous springs nearby — was, in 480 BC, a narrow corridor between a cliff face and the Malian Gulf. At its narrowest, the pass was perhaps 15 metres wide. A small force positioned there could hold against an army of any size, as long as the army could only approach frontally.

The Persian Invasion

Xerxes I of Persia assembled a massive force for an invasion of Greece. The ancient sources — primarily Herodotus, writing some decades after the event — give wildly inflated numbers. Modern historians estimate between 100,000 and 300,000 fighting men. King Leonidas, leading a force described by Herodotus as 300 Spartans plus several thousand allied Greek troops, was sent to Thermopylae as an advance guard.

The Three Days

For two days, the Greek force held the pass. Persian numerical superiority was irrelevant — only so many men could fight at once. The Persians sent in their best troops: the Medes, then the Cissians, then the elite Immortals. All were pushed back with severe losses. On the evening of the second day, a Greek named Ephialtes informed Xerxes of a mountain path bypassing the pass. A Persian force marched through the night along this path. Greek defenders posted to guard it withdrew as the Persians approached.

The Last Stand and the Inscription

At dawn on the third day, Leonidas learned that the pass was being outflanked. Allied Greek contingents were dismissed. The Spartans, reinforced by the Thespians who chose to remain, held their position until surrounded and killed. Leonidas was killed in the fighting.

An epigram attributed to the poet Simonides was placed at Thermopylae. The most commonly rendered translation: 'Go, tell the Spartans, stranger passing by / That here, obedient to their laws, we lie.' The inscription does not claim victory. It claims obedience — to law, to Sparta, to the requirement that a Spartan warrior does not retreat.

What Thermopylae Accomplished

The battle did not stop the Persian invasion. The military turning point came at the Battle of Salamis in September 480 BC, where the Athenian fleet destroyed the Persian naval force. Thermopylae's military contribution was to buy approximately three days for Greek preparations at Salamis. Whether the stand was heroic sacrifice or strategic calculation, it entered Greek cultural memory immediately and has never left since.