Note:  Do not rely on this information. It is very old.

Leonidas I

Leonidas I., King of Sparta, son of Anaxandrides and 17th of the Agid kings, succeeded his half-brother, Cleomenes I., about 491 B.C. He was given the command of the force which was to make a stand at the pass of Thermopylae against the army of Xerxes in 480 B.C. Herodotus says that this force consisted of 5,000 men, of whom 300 were picked Spartans. It was through the influence of Leonidas that this line of defence was not abandoned, and even when it was known that information had been given to the Persians which enabled them to turn it he refused to desert his post. He fell early in the fight, but his body was rescued after a sharp struggle.