Demaratus: Spartan King Turned Persian Advisor
A Spartan king sits at Xerxes’ side as Persian ships sail for Greece. He’s not a prisoner—he’s their advisor.

Salvator Rosa — "Self-Portrait" (ca. 1647), public domain
A Spartan King, Exiled to Persia
Demaratus, once king of Sparta, is banished after a bitter political feud. Rather than accept disgrace, he flees to Persia—the sworn enemy of his homeland. Decades later, Greeks are stunned to see him at Xerxes’ side, offering counsel as the Persian armies mass to invade Greece.
Outsider at the Heart of Power
Cast out at home, Demaratus builds a new identity in the opulent Persian court. He earns the king’s trust, warning Xerxes not to dismiss the resolve of the Spartans. Herodotus records him telling the Great King that Spartan laws will force his countrymen to fight, even if outnumbered or doomed.
A Warning That Echoed at Thermopylae
Xerxes ignored much of Demaratus’ advice, but the king’s defiance foreshadowed the stand at Thermopylae. Demaratus’ fate is largely lost to history—but his words outlived him, caught between two worlds, loyal to neither.
Demaratus was driven out of Sparta, stripped of his crown by political enemies. Instead of fading away, he fled across the Aegean and landed at the Persian court, where he became a trusted counselor to the Great King. When Xerxes prepared to invade Greece, Demaratus warned him not to underestimate his old countrymen—the Spartans would fight, he insisted, 'no matter their numbers.'