The document provides information on key figures and battles in the Greco-Persian Wars. It discusses Darius I who organized the Persian Empire and planned to conquer Greece but died in 486 BC. It then discusses Xerxes who personally led the second Persian invasion of Greece in 480 BC against King Leonidas of Sparta and his 300 soldiers at the Battle of Thermopylae. The Battle of Thermopylae was fought over three days between the Greek city-states led by Leonidas and the vast Persian Empire of Xerxes, resulting in a Persian victory.