The reliable part of Herodotus’ story is probably confined to the raising of the question whether or not some diversion against Sparta should be attempted. Into this account Herodotus has inserted a detail borrowed from a similar strategic question of his own day.
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.
Near this point in Mid Bœotia the invader from the north is faced by a barrier of a composite character, which, though not homogeneous, is one of the most effective in the whole of Greece. From the west the spurs of Helicon came down to the marshy expanse of Lake Kopais, a hundred square miles of shallow reed-covered mere, when the winter rains had raised it to its full height. From Kopais to the Euripus extended a narrow mountainous region, never rising to any great height, but exceedingly rough and broken, and affording no way of passage through it better than a mere track.
The consequence of this natural formation of the country was that an invader from the north was confined in his advance to the narrow breadth of land between Helicon and Kopais. So this mere ribbon of country became the great battle-ground of Greece, and on it the fate of the land was again and again decided at Chæronea, Koronea, and elsewhere. This part of the great northern route may be said to end at Thebes, which town, like Larisa and Lamia, was not merely a point where important roads converged, but also a point which must be passed in the passage from the North. To it came the great road which has just been described, and also a hardly less important road, which ran from Chalkis on the Eastern sea, and was continued through it to Kreusis on the Corinthian Gulf. Thebes was thus one of the great strategic positions in Greece.
Xerxes’ main object after taking Thermopylæ was to strike at Attica. Two minor objects had to be attained by the way; the punishment of the Phocians, and the plunder of Delphi.
The Phocians were the only people in the north, so Herodotus says, who did not medize. The Bœotians, wavering if not disloyal before, doubtless medized en masse after Thermopylæ had shown them the insincerity of the Council at the Isthmus with regard to the defence of the north. It is difficult to account for the Phocian attitude. H. viii. 30. Herodotus says they were simply actuated by the desire to take the opposite side to the Thessalians. It is possible that they dared not trust to the mercy of the Persian, seeing they had taken part in the defence of Thermopylæ. Besides, their own deadly foes were in the enemy’s camp. Whatever their motive was, H. viii. 30, ad fin. they took the moral ground of refusing to be traitors to their fatherland, and rejected the offer of the Thessalians to save them at a price.
The first step in the march south which Herodotus describes is the invasion of Phocis. H. viii. 31. A body of troops, under the guidance of the Thessalians, made their way into Doris, that dreary little upland plain at the head of the Kephissos basin. The route taken must have been by the Asopos defile. Doris was left unharmed. It had medized; and, besides, the Thessalians intervened on its behalf. Its poverty may have had something to do with its salvation on this occasion.[148]
From Doris the invaders passed into Phocis. There is no natural boundary between the two plains; and the records of the history of this region, dim though they are, point to a frequent shifting of the frontier. The Phocians had one retreat to which they could always resort; and, before the invasion was on them, they took to the heights of Parnassus, whose great humped mass rises more than seven thousand five hundred feet above the plain. It was evidently the accustomed refuge of the race. They had adopted the same plan at the time of the undated Thessalian attack on their country.