Battle of Thermopylae at Thermopylae, the Persians sent a mounted scout to reconnoitre. The Greeks allowed him to come up to the camp, observe them, and depart. Xerxes found the scout's reports of the size of the Greek force, and that the Spartans were indulging in callisthenics and combing their long hair, laughable. Seeking the counsel of Demaratus, an exiled Spartan king in his retinue, Xerxes was told the Spartans were preparing for battle, and it was their custom to adorn their hair when they were about to risk their lives. Demaratus called them "the bravest men in Greece" and warned the Great
Leonidas I stood in higher regard, nor was Sparta less powerful in 478 BC than it had been in 481 BC. This selection of Leonidas to lead the defense of Greece against Xerxes' invasion led to Leonidas' death in the Battle of Thermopylae in 480 BC. Upon receiving a request from the confederated Greek forces to aid in defending Greece against the Persian invasion, Sparta consulted the Oracle at Delphi. The Oracle is said to have made the following prophecy in hexameter verse: In August 480 BC, Leonidas marched out of Sparta to meet Xerxes' army at Thermopylae with a small force