The historian Herodotus tells us that, with his army suffering over 10,000 losses (including two of his own brothers killed while fighting in the Immortals) at the hands of the stubborn Leonidas, and his fleet reduced by anywhere from 300-400 ships thanks to the aggressive tactics of Themistocles at Artemisium and the whims of Poseidon off Euboea, Xerxes was in a fit of both anger and depression. How much longer could this stalemate continue? As it turned out, not long at all.
At the end of the second day’s slaughter of yet more Persian soldiers it would be treachery rather than tactics that won the day for Xerxes. Ephialtes, a Greek who sought riches and favor in Xerxes’ court, revealed an ancient goat trail that led around the pass and allowed an army to approach from behind, effectively trapping whoever remained. During the night Xerxes sent 10,000 Immortals winding their way along the path to come down on the rear of the Greek positions. Having been warned of the enemy’s approach by the Phocians who were guarding the trail, Leonidas ordered the defenders to withdraw before they were destroyed. But he and his surviving Spartans would remain. His decision may have been influenced by a prophecy that said for Greece to be saved a Spartan king of his lineage must die in battle. Perhaps his final stand was to both buy time for the rest of the army to escape and put a good distance between them and any subsequent pursuing Persians, especially horsemen, while writing his name and those of his defenders in glory. What is sometimes forgotten, though, is that what remained of the 700 Thespians under their irascible commander, Demophilus, refused to retreat, but chose to stand by their Spartan allies to the end. It must have been a sublime scene as the Spartans and Thespians marching one way to die said their farewells to the Greeks who marched the other way to live. Inevitably the Persians, having outflanked the remaining Greeks and formed up on their rear, overwhelmed the surrounded defenders of Thermopylae and finished them off with arrows.
King Leonidas of Sparta was dead, his head ignominiously displayed on a pike as a warning from the angry Xerxes that if his vast army could defeat the vaunted Spartans, then the rest of Greece would be wise to bend the knee. But first he had a score to settle with Athens. And the way to Xerxes’ retribution was now open. The name Ephialtes literally means “nightmare” in Greek today.
**[Author’s note: At the location of the last stand at Thermopylae, visitors can still find a monument erected by the ancient Spartans to commemorate Leonidas’ heroic band of warriors. On it is inscribed this simple epitaph: “Go tell the Spartans, strangers passing by, that here obedient to their laws we lie.”]**
With no land army left to protect, and having fought a stubborn naval action at Artemisium and inflicting substantial losses on the enemy, the Athenians now rowed south for the Bay of Salamis, with the wounded but still numerically formidable Persian armada in hot pursuit. The armies of the Peloponnese—principally from Sparta, Corinth and Argos—now sought to defend their homes at the six-mile isthmus of Corinth that led into the southern peninsula. By September 480 BC, only 20 out of the roughly 1,000 free Greek poleis before the Persian invasion remained out of Xerxes’ clutches. The desperate Athenians knew that there would be no Marathon this time. In 490 BC Miltiades had been outnumbered three-to-one, but the enemy now was ten times the size of Darius’ expedition. It was as if the glorious victory just ten years before never happened. This time there’d be no stopping the Persians from advancing on Athens. The city’s fate was sealed.