Leonidas (c. 530-480 BC) was king of the city of Sparta from 490 BC. until his death in the Battle of Thermopylae against the Persian army in 480 BC. Although Leonidas lost the battle, his death at Thermopylae was considered a heroic sacrifice because he sent most of his army when he realized that the Persians had overtaken him. Three hundred of his Spartans stayed with him to fight and die. Almost everything known about Leonidas comes from the work of the Greek historian Herodotus (ca. 484 BC 425 BC).