Book 8 traces the movements of the Greek and Persian forces after the battle of Thermopylae, as Xerxes continues his march toward Attica. After an indecisive naval engagement at Artemisium, the Persians proceed through Boeotia and devastate the Attic countryside, burning the Athenian acropolis. The Book culminates in the decisive victory of the Greek fleet at Salamis, which induces Xerxes to withdraw from Greece and return to Asia, leaving his general Mardonius behind with 300,000 troops to continue the campaign against the Athenians and Peloponnesians.

While the Greek forces under Leonidas were preparing to defend Thermopylae, the Greek confederacy sent a fleet of 271 large warships under the command of a Spartan, Eurybiades, to Artemisium on the northern tip of Euboea. The Greek allies refused to serve under an Athenian even though the Athenians provided more than half the vessels in the armada. Realizing that the unity in the face of the Persian threat was Greece’s only hope for salvation, the Athenians waived their claim to command in the interest of national survival.

Arriving at Artemisium, the Greeks panicked when they discovered that the Persian fleet anchored at Aphetae on the opposite coast was much more formidable than they expected.