King Leonidas of Sparta: Life, Reign, and Legendary Stand at Thermopylae

King Leonidas of Sparta, born around 540 BC into the Agiad dynasty, was the third son of King Anaxandridas II. Not expected to inherit the throne, he underwent the rigorous Agoge training. After the deaths of his half-brother Cleomenes I and brother Dorieus, Leonidas became king around 490 BC, marrying Cleomenes' daughter Gorgo. During the Greco-Persian Wars, Leonidas led a Greek coalition to defend the pass of Thermopylae in 480 BC against Xerxes' massive invasion force. Despite holding for two days, a local traitor named Ephialtes revealed a mountain pass, allowing Persians to outflank the Greeks. Leonidas dismissed most allies but stayed with his 300 Spartan bodyguards, 700 Thespians, and 400 Thebans. They fought to the death, killing an estimated 20,000 Persians. Leonidas fell in battle, succeeded by his son Pleistarchus. His remains were later recovered and placed in the Leonidaion. The battle became legendary, celebrated in art by Jacques-Louis David and in the 2006 film '300'.