Also on the following day, the narrow Thermopylae isthmus was getting in the way of the Persian army, which suffered further heavy losses. Despite their huge numerical advantage, the Persians gained nothing. When Xerxes began to wonder how further fighting at Thermopylae would affect the morale of his army, he was approached by Ephialtes, a Greek from Trachis, who, hoping for a lavish reward, revealed to him that there was a hidden path to bypass the Thermopylae isthmus and get to the rear of the Greeks.
