Battle of Thermopylae 480 BC: 300 Spartans vs the Persian Empire

By Echoes of Battle

Leonidas and a Greek coalition could not stop Xerxes forever. For three days, terrain, discipline and a final rearguard made sure the invasion would never be remembered as an easy conquest.

Leonidas and a Greek coalition could not stop Xerxes forever. For three days, terrain, discipline and a final rearguard made sure the invasion would never be remembered as an easy conquest.

By Echoes of Battle — Updated October 2, 2026

The famous number is 300. The real story begins with more men, a harder strategic problem and a narrow strip of ground where the size of an army mattered less than the space in which it could fight.

In 480 BCE, Xerxes I led the Achaemenid Persian Empire into Greece. A coalition of Greek city-states sent roughly 7,000 troops north under the Spartan king Leonidas. Their chosen position was Thermopylae—the “Hot Gates”—where mountain and sea compressed the road into a defensible pass.

Ground as a weapon

On open terrain, Persian numbers could envelop the defenders. In the pass, only a limited front could engage at once. Greek hoplites fought in dense formation, overlapping shields and projecting long spears into the confined approach. The geography did not erase Persia’s advantage, but it gave the defenders a way to spend time at a terrible price.

For two days, assaults failed to break the line. Even elite Persian formations could not easily turn the Greek flank while the coastal passage held. The Greek stand at Thermopylae also worked alongside naval operations at nearby Artemisium; neither battlefield existed in isolation.

The legend says “300.” The last stand also belonged to 700 Thespians—and to a much larger coalition that held the pass before the final day.Myth, corrected

The path around the wall

The position failed when Ephialtes, a local man, revealed a mountain track around it. Persian troops moved along the path and threatened the defenders from behind. Once Leonidas learned the pass had been turned, he released much of the coalition to withdraw.

The final rearguard included the 300 Spartans, 700 Thespians and Theban troops, along with others whose precise number remains debated. Their stand could not reverse the outcome. It could only delay it—and protect the retreat of men who would fight again.

A defeat with an afterlife

Thermopylae ended in Persian victory, and the road into central Greece opened. Yet the campaign did not end there. Greek resistance continued, and later victories at Salamis and Plataea broke the invasion.

What survived Thermopylae was not a simple lesson that courage always wins. The deeper lesson is more exacting: terrain can reshape a contest, alliances matter, and a tactical defeat can still buy time for a larger strategy. The battle became legend because its defenders understood what they could no longer save—and chose what they still could.

The men who held the pass

Leonidas was about sixty years old, one of Sparta's two kings, and he knew exactly what Thermopylae would cost. The 300 men he brought were hand-picked — and according to Herodotus, every one of them was a father with a living son. Sparta was not sending its future to die; it was sending men whose families would survive them.

It was never just 300. Roughly 7,000 Greeks held the pass: Thespians, Thebans, Phocians, men from half a dozen cities, plus helot attendants. The 700 Thespians are the forgotten heroes of Thermopylae — when Leonidas dismissed the allies on the final morning, the Thespians refused to leave. They died with the Spartans, and history barely remembers their name.

The pass itself was the real Greek general. At the "Hot Gates" — named for the sulfurous hot springs — the mountains squeezed the coastal road to the width of a single cart. The Greeks rebuilt an old Phocian wall across it. Numbers meant nothing in a corridor that narrow; only discipline did.

Three days at the Hot Gates

On the first day Xerxes threw his Medes and Cissians at the wall. They were cut down. Then he sent the Immortals, his 10,000-strong guard — and they were cut down too. When a Persian warned that Persian arrows would blot out the sun, the Spartan Dienekes answered: "Then we shall fight in the shade." It may be legend. It is also exactly the kind of thing a Spartan would say.

The second day went no better for Persia. Herodotus claims Xerxes leapt from his throne three times watching his best troops break against the wall. That night, a Greek traitor named Ephialtes came to the Persian camp with the war's most valuable piece of information: a mountain path, the Anopaea, that bypassed the pass entirely — for a price.

At dawn on the third day, the Phocian guards on the mountain path were surprised and scattered. Leonidas knew what was coming. He dismissed most of the allies — some say to spare them, some say the omens were bad — and kept the 300 Spartans, the 700 Thespians, and 400 Thebans. They fought the Persians head-on, then fell back to a small hill and fought surrounded, with swords, then spears broken to daggers, then hands and teeth, as Herodotus tells it. Leonidas fell early; the fight over his body was one of the fiercest of the day. By noon it was over. Persian losses were enormous — Herodotus says 20,000, which is almost certainly inflated, but even a fraction of that was a stunning price for one narrow pass.

What the numbers really were

Herodotus gives Xerxes 2.6 million men, a figure no modern historian takes seriously — feeding that many mouths in 480 BC was physically impossible. Serious estimates put the Persian invasion force between 70,000 and 300,000 combatants. Against roughly 7,000 Greeks, the odds were still overwhelming.

And the delay mattered more than the casualty count. While Leonidas held the pass, the Greek fleet held the straits at Artemisium. When Thermopylae fell, the fleet withdrew in good order — to Salamis, where a few weeks later the Greeks destroyed the Persian navy and effectively ended the invasion. The 300 bought that with their lives. It was, by any honest measure, a fair trade.

Salamis: what the sacrifice bought

Thermopylae bought roughly three weeks. Xerxes marched into a nearly empty Athens — the Athenians, on Themistocles' urging, had abandoned the city for the island of Salamis and the Peloponnese. The Persians burned the Acropolis and its temples. It looked like the end of Greece.

It was a trap. Themistocles had convinced the Greek commanders to fight in the narrow straits of Salamis, where the huge Persian fleet could not use its numbers — the same logic as Thermopylae, applied to water. He even sent a false message to Xerxes, posing as a traitor, urging the Persians to attack before the Greeks could slip away. Xerxes took the bait. In the cramped straits his ships collided with each other while the Greek triremes rammed them methodically, one by one. By evening the Persian navy was wrecked.

Xerxes left for Asia that autumn, leaving his general Mardonius with a picked army to finish the job. He never did. The next summer, in 479 BC, a combined Greek army destroyed Mardonius at Plataea on land, while the Greek fleet smashed what remained of Persian sea power at Mycale on the same campaign. The invasion was over — and it had been Thermopylae's delay, plus Artemisium's, that kept a Greek fleet and army in existence long enough to win those battles. Leonidas could not have known any of this. He bought the time anyway.

The epitaph on the hill

On the small hill where the last stand was fought, the Greeks raised a stone lion and carved the words attributed to the poet Simonides: "Go tell the Spartans, stranger passing by, that here, obedient to their laws, we lie." It is the most famous epitaph in military history, and it is worth reading carefully — it does not celebrate victory. It celebrates obedience. The Spartans are not praised for winning. They are praised for staying.

Almost everything we know about the battle comes from Herodotus, writing about fifty years later, and he is an uneven witness — precise on the terrain, theatrical with the numbers, credulous with the anecdotes. Later writers embroidered further. Strip away the embroidery and the core holds: a small Greek force used impossible terrain to delay a vast invasion, at the cost of its own annihilation, and the delay changed the war.

One irony for the visitor: the Thermopylae of today looks nothing like the Thermopylae of 480 BC. The sea has receded over two and a half millennia, and the pass — once a cart's width between cliff and water — is now a broad plain several kilometers wide. The hot springs still steam, and the modern monument still draws travelers. But the ground that was the weapon is gone. What remains is the story, which turned out to be the more durable fortification anyway.