Xerxes asked his guides if there were any other outlet for the Peneus into the sea, and they, with their full knowledge of the matter, answered him: “The river, O king, has no other way into the sea, but this alone. This is so because there is a ring of mountains around the whole of Thessaly.” Upon hearing this Xerxes said: “These Thessalians are wise men; this, then, was the primary reason for their precaution long before when they changed to a better mind, for they perceived that their country would be easily and speedily conquerable. It would only have been necessary to let the river out over their land by barring the channel with a dam and to turn it from its present bed so that the whole of Thessaly, with the exception of the mountains, might be under water.” This he said with regard in particular to the sons of Aleues, the Thessalians who were the first Greeks to surrender themselves to the king. Xerxes supposed that when they offered him friendship they spoke for the whole of their nation. After delivering this speech and seeing what he had come to see, he sailed back to Therma.