Leonidas was the Spartan king who famously led a small band of Greek allies at the Battle of Thermopylae in 480 BCE where the Greeks valiantly defended the pass through which the Persian king Xerxes sought to invade Greece with his massive army. Ultimately, Leonidas and his men were wiped out, but they bought the Greek city-states valuable time and gave an inspirational example, not only of what Greek hoplites could achieve against the invading forces but also of the price Greeks were willing to pay to maintain their freedom from foreign oppression.
Herodotus in his Histories describes the family lineage of Leonidas which could be traced back 20 generations to the mythical hero Hercules. Leonidas' father was the Spartan king Anaxandrides, himself the son of King Leon. Anaxandrides, however, had some problems in producing an heir after his first wife proved barren. The Spartan Ephors and Elders, to protect the royal lineage, forced Anaxandrides to take a second wife. She did give birth to a son, Cleomenes, but in a strange twist Anaxandrides' first wife announced she was also now pregnant and another son, Dorieus, was born. Then, shortly after, the first wife again gave birth sometime in the 540's BCE to Leonidas and Kleombrotus, some saying the latter were twins.
As Leonidas had two older brothers it seemed unlikely he would represent the royal House of Agiad and become one of the two Spartan kings. However, he did just that following the death of Doreius on campaign in Sicily and the mysterious suicide (put down to bad drinking habits) of Cleomenes, who left no heir. Leonidas was married to Gorgo, Cleomene's daughter, and the death of her father meant Leonidas became king, sometime around 490 BCE.
Leonidas would have been in his sixties by the time of Thermopylae and undoubtedly an experienced military commander, although we know nothing of his previous commands. Following Xerxes' proposed land invasion of mainland Greece in 480 BCE Leonidas was selected to lead a small contingent of Spartan hoplites - some 300 hand-picked men with male heirs - to defend the pass of Thermopylae and hold the invading force until more troops could be mustered. The Spartans at this time were involved in the sacred Karneia festival and so, theoretically, could not go to war until it was over. Sparta could well have fielded up to 8,000 hoplites but not during the Karneia. The 300 Spartans were joined by troops form various other city-states to make up a force of up to 7,000 men, woefully inadequate to halt Xerxes' army of 80,000.
Thermopylae, 150 km north of Athens, was an excellent choice as the point to defend Greece, as there mountains rolled down into the sea leaving only a narrow pass along the coast. Nevertheless, Xerxes was so confident of success that he sent a messenger to Leonidas to ask for the Greeks to surrender and lay down their arms. The Spartan king's laconic reply was 'molōn labe' - come and get them.
With Leonidas leading from the front and the hoplites fighting in their tight phalanx formation, they took full advantage of their superior armour and weapons and managed to hold the vast Persian army for two days. However, betrayed by a local shepherd who told the Persians of a mountain path which would allow them to get behind the Greek lines, things looked grim for the defenders. Leonidas ordered the bulk of his force to withdraw and kept with him only the Spartans, Thespians, and Thebans in order to make a last stand and provide a rear-guard action.
Ultimately, though, the Greek forces were wiped out to a man and Apollo's oracle at Delphi had been proved right when she had stated that either Sparta or one of her kings must fall. After the battle Xerxes demanded that Leonidas' head be put on a stake for public display, a highly dishonourable act and against all rules of warfare at that time.
Leonidas' son Pleistarchus became king on his father's death but due to his young age Pausanius acted as regent. The Greeks, within a year, gained revenge for Thermopylae with victories at Salamis and Plataea; the latter even led by Pausanius, nephew of Leonidas. Xerxes' invasion was emphatically rebuffed and those who fell at Thermopylae were not forgotten. A monument was set up at the site with the words of Simonedes' epitaph stating: 'go tell the Spartans, you who read: We took their orders and here lie dead'. A stone lion was also placed in memory of Leonidas and his men. Forty years after the battle the king's remains were exhumed and returned to Sparta where they were given proper burial and a hero-shrine was also established in his honour.
In ancient art, Leonidas is quite possibly the subject of a surviving marble statue from the acropolis of Sparta, 490-480 BCE. Resplendent in a crested Corinthian helmet, his face, which would have had inlaid eyes, depicts the grim determination for which the fallen king became a legend.