Battle of Thermopylae

Xerxes quickly learned that the Greeks stood at Thermopylae.

An excerpt from the article 31 facts about Battle of Thermopylae

He sent a single scout to inspect the Spartan encampment and, upon his return, gave an account of what he saw. Xerxes underestimated the small Greek army - the Persians were crushingly outnumbered-and paid no heed to the warnings of the exiled Spartan king Demaratos, who was in his camp and well aware of the fighting value of the Spartan hoplites. He called them the bravest men in the world.