King Leonidas of Sparta and the Battle at Thermopylae

CIRCA 1986: Jacques-Louis David (1748-1825), Leonidas at Thermopylae. (Photo By DEA / G. DAGLI ORTI/De Agostini/Getty Images). De Agostini/Getty Images

Leonidas was a 5th century B.C. military king of the Greek city-state of Sparta. He is most well known for bravely leading a small force of Greeks, including the famous 300 Spartans, along with a few hundred Thespians and Thebans against the much larger Persian army of Xerxes, at the pass of ​Thermopylae in 480 B.C. during the Persian Wars.


Leonidas was the third son of Anaxandridas II of Sparta. He belonged to the Agiad Dynasty. The Agiad Dynasty claimed to be decedents of Heracles. Thus, Leonidas is considered a decedent of Heracles. He was the half-brother of the late King Cleomenes I of Sparta. Leonidas was crowned King after the death of his half-brother. Cleomenes' died of a suspected suicide. Leonidas was made king because Cleomenes had died without a son or another, closer male relative to serve as a suitable heir and reign as his successor. There was also another tie between Leonidas and his half-brother Cleomenes: Leonidas was also married to Cleomenes' only child, the wise Gorgo, Queen of Sparta.

Battle of Thermopylae

Sparta received a request from the confederated Greek forces to help in defending and protecting Greece against the Persians, who were powerful and invading. Sparta, led by Leonidas, visited the Delphic oracle who prophesized that either Sparta would be destroyed by the invading Persian army, or the king of Sparta would lose his life. The Delphic Oracle is said to have made the following prophecy:

For you, inhabitants of wide-wayed Sparta,
Either your great and glorious city must be wasted by Persian men,
Or if not that, then the bound of Lacedaemon must mourn a dead king, from Heracles' line.
The might of bulls or lions will not restrain him with opposing strength; for he has the might of Zeus.
I declare that he will not be restrained until he utterly tears apart one of these.

Faced with a decision, Leonidas chose the second option. He was not willing to let the city of Sparta be wasted by the Persian forces. Thus, Leonidas led his army of 300 Spartans and soldiers from other city-states to face Xerxes in Thermopylae in August of 480 BC. It is estimated that the troops under Leonidas’ command numbered about 14,000, while the Persian forces consisted of hundreds of thousands. Leonidas and his troops fended off the Persian attacks for seven days straight, including three days of intense battle, while killing off large numbers of enemy troops. The Greeks even held off the Persian’s elite Special Forces known as ‘The Immortals.’ Two of Xerxes brothers were killed by Leonidas’ forces in battle.

Eventually, a local resident betrayed the Greeks and exposed a back route of attack to the Persians. Leonidas was aware that his force was going to be flanked and taken over, and thus dismissed the vast majority of the Greek army rather than suffer more high casualties. Leonidas himself, however, remained behind and defended Sparta with his 300 Spartan soldiers and some other remaining Thespians and Thebans. Leonidas was killed in the resulting battle.

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Gill, N.S. "King Leonidas of Sparta and the Battle at Thermopylae." ThoughtCo, Aug. 26, 2020, Gill, N.S. (2020, August 26). King Leonidas of Sparta and the Battle at Thermopylae. Retrieved from Gill, N.S. "King Leonidas of Sparta and the Battle at Thermopylae." ThoughtCo. (accessed May 30, 2023).