The effect on Athens was electric. The people were filled with pride and self-confidence, and they found in Themistocles a leader of genius. He realised that the Persians would return, and persuaded the Athenians to build a large fleet, which proved the salvation of Greece. In 480 B.C. the long expected invasion came. Xerxes, who had succeeded Darius, brought an immense army and many ships. Yet even at this crisis the Greeks refused to work together, and some states actually submitted to Xerxes. The Persian advance was checked momentarily at the pass of Thermopylae, where Leonidas and his three hundred Spartans were slain, after performing prodigies of valour. This stand was commemorated by the famous epitaph : Go tell the Spartans, thou that passest by, That here, obedient to their laws, we lie. The decisive battle took place off the west coast of Attica. The strategy of Themistocles lured the Persian fleet into the straits of Salamis, where the ships were crowded together and got in each other's way. Then the allied fleet, the greater part of which consisted of Athenian vessels, attacked and won a complete victory (480 B.C.). Xerxes hurried back to Asia, but left behind a large army which was beaten at Platsea in 479 B.C. by Spartan courage and Spartan leadership. The final repulse of the Persians meant the victory of freedom; not only of political freedom, but freedom of thought, for the Greek criticism was justified that " In the Persian Empire all are slaves except one." Henceforth Greece was to provide future ages with the example of a nation in which religion and privilege were no longer exempt from criticism. Reason would be free to " follow the argument whithersoever it leads."