The way in which the advance by sea should be conducted being settled, it was necessary to decide upon the line or lines of advance by land. From Thermopylæ to the Attic border the Greek military highway is defined with singular clearness by the nature of the country. Œta forms the first barrier to be passed. The question of the utility of the Asopos ravine has been already discussed. For the purposes of a large army it is impracticable. Infantry could only pass through it in single file; and even a slight accident, or a slight rise in the stream, would block it. For a lightly equipped column with numbers not so large as to make it impossible for it to live on the country in its passage of the Dorian and Phocian plains, it would be a practicable route under circumstances such as existed at the time. Little opposition was to be expected; and it would be merely the question of a day or two before a junction could be effected with the main army, which would reach Parapotamii where the Phocian plain ends and the Bœotian begins, by the great route by way of Hyampolis. Besides the Asopos ravine there were three other routes from Thermopylæ southwards. The first of these led out of the pass up a steep ascent of one hour, and crossed the range of Œta, by way of the modern Boudenitza, to the ancient Elatæa. It is a mere mountain path, a way which an army without a heavy baggage train might adopt in an emergency, or by which a force defeated at Thermopylæ might secure its retreat. The second left the coast road near Thronion and passed up the valley of the Boagrios river, at the head of which it crossed the mountain ridge, and descended to Elatæa. It was certainly of importance in later times, though not fitted for the passage of a heavy baggage train, and difficult for cavalry. Hence, probably, there is no trace of its having been used by the Persian army on this occasion. The route by Atalanta and Hyampolis is admirably adapted for the advance of a large force. It presents but few difficulties to cavalry or baggage-train, and affords but few facilities to the defence. In this very part of his history Herodotus, in his excursus on the pre-existing relations between the Thessalians and Phocians, gives an example which shows pretty clearly that it was the route by which incursions of the Thessalian cavalry had to be feared. In an undated, but presumably recent war between the two peoples, ◆H. viii. 28.◆ the Phocians had inflicted a severe defeat on the raiding cavalry in the pass near Hyampolis. They had dug a trench across it, filled it with large pottery, and covered it with earth. Into this the Thessalian horsemen had fallen, and had incurred signal disaster. The three minor routes join this major route at Parapotamii. There is, however, a loop of the main road, which, starting from Hyampolis, passes over a ridge to Orchomenos and joins the main road again outside the mountain gate at Parapotamii. #ROUTE THROUGH BŒOTIA.#