Leonidas I

The sixteenth Agiadai king of the city of Sparta who ruled from 490-480 BCE.

Sparta traditionally had two kings who ruled jointly; one king was required to be a descendant of king Agis I and the other was required to be a descendant of king Eurypon (respectively known as the Agiadai and the Eurypontidai).

Beginning with Leonidas I, the names and dates for the Spartan kings became a part of the historical record and are generally accepted as factual; prior to Leonidas I, the dates for the Spartan kings are extrapolated back from historical times to approximate the time periods in which each king ruled.

Leonidas I is the most famous Spartan king because he fought to the death against the Persian army at Thermopylae in 480 BCE; after the Persian king, Xerxes, had advanced down the eastern coast of Greece, Leonidas made his stand at the narrow passage of Thermopylae; Leonidas led an army made up of Greeks from different districts of the Peloponnesian Peninsula but the command and the responsibility was strictly Spartan.

When the Greeks saw the Persians approaching, the Phokians (Phocians) and the Lokrians (Locrians) wanted to withdraw but Leonidas commanded that they stand and fight; the Persians thought that if the Greeks saw the sheer size of their army they would retreat, so the Persians waited for five days before they mounted their first attack.

Initially the Persians sent their allies, the Medes and the Kissians (Cissians), to dislodge the Greeks but they were beaten back with heavy losses; king Xerxes then sent his chosen troops, the Immortals, against the Greeks but they too were slaughtered (the Greeks used a tactic that the Persians had never encountered before: the Greeks would stop fighting and turn to flee from the Persians; the Persians would shout and rejoice thinking that they had won the battle and then chase after the fleeing Greeks without re-forming into their fighting formations; the Greeks would then turn back to the fight and, with the Persians caught off guard, plow into the Persian attackers with no mercy).

With no chance of winning a frontal assault, the Persians were at a loss as to how to defeat Leonidas until a Greek traitor named Ephialtes of Malis showed the Persians a mountain trail that would lead them behind the Greek defenses; Leonidas and most all of the defenders were killed in the resulting sneak attack.

• Histories, book 7, chapter 207+