In 480 B.C., Xerxes I, king of the Persian Empire, led a vast and uncountable army intent on the domination of Europe. Only a tiny collection of Greek city-states stood in his path. At Thermopylae the Persians annihilated a small holding force commanded by King Leonidas of Sparta, then quickly marched on to Athens, reducing the city to ruins. Outnumbered and beset by treachery, Sparta, Athens and their allies gathered near the town of Plataea for...