High Quality Content by WIKIPEDIA articles! Demaratus was a king of Sparta from 515 until 491 BC, of the Eurypontid line, successor to his father Ariston. As king, he is known chiefly for his opposition to the other, co-ruling Spartan king, Cleomenes I. When Cleomenes attempted to make Isagoras tyrant in Athens, Demaratus tried unsuccessfully to frustrate his plans. In 501 BC, Aegina was one of the states which gave the symbols of submission (earth and water) to Persia. Athens at once appealed to Sparta to punish this act of medism, and Cleomenes I crossed over to the island to arrest those responsible. His first attempt was unsuccessful, due to interference from Demaratus, who did his utmost to bring Cleomenes into disfavour at home. In retaliation, Cleomenes urged Leotychidas, a relative and personal enemy of Demaratus, to claim the throne on the ground that the latter was not really the son of Ariston, but of Agetus, his mother's first husband. Cleomenes bribed the Delphic oracle, to pronounce in favor of Leotychidas, who became king in 491 BC.