In the first place, Artemisium is contracted from a wide space of the Thracian sea into a narrow frith, which lies between the island of Sciathus and the continent of Magnesia.  From the narrow frith begins the coast of Euboea, called Artemisium, and in it is a temple of Diana.  But the entrance into Greece through Trachis, in the narrowest part, is no more than a half plethrum in width:  however, the narrowest part of the country is not in this spot, but before and behind Thermopylae; for near Alpeni, which is behind, there is only a single carriage-road, and before, by the river Phoenix, near the city of Anthela, is another single carriage-road.  On the western side of Thermopylae is an inaccessible and precipitous mountain, stretching to Mount Oeta, and on the eastern side of the way is the sea and a morass.  In this passage there are hot baths, which the inhabitants call “Chytri,” and above these is an altar to Hercules.  A wall had been built in this pass, and formerly there were gates in it.  The Phocians built it through fear, when the Thessalians came from Thesprotia to settle in the AEolian territory which they now possess:  apprehending that the Thessalians would attempt to subdue them, the Phocians took this precaution; at the same time, they diverted the hot water into the entrance, that the place might be broken into clefts, having recourse to every contrivance to prevent the Thessalians from making inroads into their country.  Now this old wall had been built a long time, and the greater part of it had already fallen through age; but they determined to rebuild it, and in that place to repel the barbarian from Greece.  Very near this road there is a village called Alpeni; from this the Greeks expected to obtain provisions.

Accordingly, these situations appeared suitable for the Greeks; for they, having weighed everything beforehand, and considered that the barbarians would neither be able to use their numbers nor their cavalry, there resolved to await the invader of Greece.  As soon as they were informed that the Persian was in Pieria, breaking up from the Isthmus some of them proceeded by land to Thermopylae, and others by sea to Artemisium.

The Greeks, therefore, being appointed in two divisions, hastened to meet the enemy; but, at the same time, the Delphians, alarmed for themselves and for Greece, consulted the oracle, and the answer given them was, “that they should pray to the winds, for that they would be powerful allies to Greece.”

The Delphians, having received the oracle, first of all communicated the answer to those Greeks who were zealous to be free; and as they very much dreaded the barbarians, by giving that message they acquired a claim to everlasting gratitude.  After that, the Delphians erected an altar to the winds at Thyia, where there is an inclosure consecrated to Thyia, daughter of Cephisus, from whom this district derives its name, and conciliated them with sacrifices; and the Delphians, in obedience to that oracle, to this day propitiate the winds.