[Note 7. Herodotus (Book VII, 213-218) tells the story of how a Greek traitor, Ephialtes, helped the Persian invaders at the Battle of Thermopylae (480 B.C.) When the Persian King, Xerxes, had begun to despair of being able tobreak through the Greek defence, Ephialtes came to him and, on being promiseda definite payment, told the King of a pathway over the shoulder of the mountainto the Greek end of the Pass. The bargain being clinched, Ephialtes led adetachment of the Persian troops under General Hydarnes over the mountainpathway. Thus taken in the rear, the Greek defenders, under Leonidas, King of Sparta, had to fight in two opposite directions within the narrow pass. Terrible slaughter ensued and Leonidas fell in the thick of the fighting.