When Cleomenes attempted to make Isagoras tyrant in Athens, Demaratus tried unsuccessfully to frustrate his plans. In 491 BC, Aegina was one of the states which gave the symbols of submission 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 grounds 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 favour of Leotychidas, who became king in 491 BC. After the deposition of Demaratus, Cleomenes visited the island of Aegina for a second time, accompanied by his new colleague Leotychides, seized ten of the leading citizens and deposited them at Athens as hostages. . Laureate head of Apollo left / Head of Prokles right, wearing Persian headdress. On his abdication, Demaratus was forced to flee. He went to the court of the Persian kingXerxes I, who gave him the cities of Teuthrania and Halisarna around Pergamum, where his descendants Eurysthenes and Procles still ruled at the beginning of the 4th century BC. He accompanied Xerxes I on his invasion of Greece in 480 BC and is alleged to have warned Xerxes not to underestimate the Spartans before the Battle of Thermopylae: Xerxes I also asked Demaratus about his knowledge of the Greeks and if they will put up a fight against the Persian army. In response Demaratus speaks favourably about the Greeks even after being deposed and exiled from Sparta: ;Greek exiles in the Achaemenid Empire Demaratus was one of several Greeks aristocrats who took refuge in the Achaemenid Empire following reversals at home, other famous ones being Themistocles and Gongylos. In general, they were generously rewarded by the Achaemenid kings, and received land grants to support them, and ruled over various cities in Asia Minor.
