In 480 BC, Xerxes, the King of Persia, led an invasion of mainland Greece. Its success should have been a formality. For seventy years, victory - rapid, spectacular victory - had seemed the birthright of the Persian Empire. In the space of a single generation, they had swept across the Near East, shattering ancient kingdoms, storming famous cities, putting together an empire which stretched from India to the shores of the Aegean. As a result of those conquests, Xerxes ruled as the most powerful man on the planet. Yet somehow, astonishingly, against the largest expeditionary force ever assembled, the Greeks of the mainland managed to hold out. The Persians were turned back. Greece remained free. Had the Greeks been defeated at Salamis, not only would the West have lost its first struggle for independence and survival, but it is unlikely that there would ever have been such and entity as the West at all.