Herodotus wrote The Histories, an inquiry into how the Persian empire and the Greek cities came to war. He was from Halicarnassus, on the coast of what is now Turkey. This is Book 7, Polymnia. Book 6 closed with Athens beating King Darius at Marathon; Darius is dead, and his son Xerxes rules from India to the Aegean.

Xerxes lashes the Hellespont — the Dardanelles — and bridges it with ships. At Abydos he looks at his millions and weeps that none will live a hundred years. Demaratus, a Spartan exile at his court, tells him Spartans fight for law, not the lash. The army cuts a canal through Athos and marches into Europe. Greece argues whether to submit or stand. At Thermopylae, Leonidas of Sparta holds the Middle Gate with three hundred Spartans and the Thespians until Ephialtes shows the Anopaia path. The Immortals, Xerxes' guard, come over. Leonidas falls. At Artemisium, off Euboea, the fleets fight. Persia is coming for Athens. A pass has bought a few days.