Leonidas I

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Leonidas I was a king of Sparta from the Agiad royal line, one of the city's two hereditary dynasties, both of which Spartan tradition traced back to the hero Heracles. He came to the throne unexpectedly around 490 BCE: he had two elder brothers, Cleomenes and Dorieus, neither of whom left a male heir, Dorieus having died campaigning in Sicily, and Leonidas was already married to Cleomenes's own daughter Gorgo, herself remembered for her own political shrewdness in the ancient sources that survive.

That succession by default rather than design is itself part of what makes Leonidas's later reputation notable: a king who reached the throne because two more direct heirs failed to produce sons, rather than through any contest for the office, went on to become the single most remembered Spartan king in the historical record, his name outlasting every other Agiad or Eurypontid ruler of the period by a wide margin. The historicity of the man himself is not in question, unlike many figures from the same broader period whose lives survive only in later legend; Leonidas's reign and death are documented by Herodotus, writing within living memory of the events.

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

When Xerxes I invaded Greece in 480 BCE, Leonidas led the Greek force sent to hold the narrow coastal pass at Thermopylae, taking with him the three hundred Spartans Spartan law assigned a king on campaign, each one chosen specifically for having living sons, together with allied troops from several other Greek states. When a local guide showed the Persians a path around the pass, Leonidas dismissed most of the allied contingents and stayed to fight a rearguard action with his own Spartans, the Thespian volunteers, and a Theban contingent he reportedly kept back against their will, buying time for the rest of the Greek force to withdraw safely.

Herodotus reports the decision was made partly on the strength of an oracle from Delphi warning that Sparta must lose either its city or one of its kings, though how far that religious framing shaped Leonidas's own actual reasoning against the plainer military logic of a rearguard action is impossible to recover at this distance. He was killed in the fighting on the pass's third day, in early August 480 BCE; Xerxes had his corpse mutilated and his head set on a stake, and his bones were later recovered and returned to Sparta, where a monument at Thermopylae itself, carrying an epitaph attributed to the poet Simonides, commemorated the stand that made his name outlast his own dynasty's other kings.