Accordingly a force was collected, which passed up the Euripus, and disembarking at Alus, on the coast of Achaea, left the ships there, and marched by land into Thessaly. Here they occupied the defile of Tempe; which leads from Lower Macedonia into Thessaly along the course of the Peneus, having the range of Olympus on the one hand and Ossa upon the other. In this place the Greek force that had been collected, amounting to about 10,000 heavy-armed men, pitched their camp; and here they were joined by the Thessalian cavalry. The commanders were, on the part of the Lacedaemonians, Evaenetus, the son of Carenus, who had been chosen out of the Polemarchs, but did not belong to the blood royal; and on the part of the Athenians Themistocles, the son of Neocles. They did not however maintain their station for more than a few days; since envoys came from Alexander, the son of Amyntas, the Macedonian, and counselled them to decamp from Tempe, telling them that if they remained in the pass they would be trodden under foot by the invading army, whose numbers they recounted, and likewise the multitude of their ships. So when the envoys thus counselled them, and the counsel seemed to be good, and the Macedonian who sent it friendly, they did even as he advised. In my opinion what chiefly wrought on them was the fear that the Persians might enter by another pass, whereof they now heard, which led from Upper Macedonia into Thessaly through the territory of the Perrhaebi, and by the town of Gonnus- the pass by which soon afterwards the army of Xerxes actually made its entrance. The Greeks therefore went back to their ships and sailed away to the Isthmus.
Such were the circumstances of the expedition into Thessaly;they took place when the king was at Abydos, preparing to pass from Asia into Europe. The Thessalians, when their allies forsook them, no longer wavered, but warmly espoused the side of the Medes; and afterwards, in the course of the war, they were of the very greatest service to Xerxes.
The Greeks, on their return to the Isthmus, took counsel together concerning the words of Alexander, and considered where they should fix the war, and what places they should occupy. The opinion which prevailed was that they should guard the pass of Thermopylae; since it was narrower than the Thessalian defile, and at the same time nearer to them. Of the pathway, by which the Greeks who fell at Thermopylae were intercepted, they had no knowledge, until, on their arrival at Thermopylae, it was discovered to them by the Trachinians. This pass then it was determined that they should guard, in order to prevent the barbarians from penetrating into Greece through it; and at the same time it was resolved that the fleet should proceed to Artemisium, in the region of Histiaeotis, for, as those places are near to one another, it would be easy for the fleet and army to hold communication. The two places may be thus described.
Artemisium is where the sea of Thrace contracts into a narrow channel, running between the isle of Sciathus and the mainland of Magnesia. When this narrow strait is passed you come to the line of coast called Artemisium; which is a portion of Euboea, and contains a temple of Artemis (Diana). As for the entrance into Greece by Trachis, it is, at its narrowest point, about fifty feet wide. This however is not the place where the passage is most contracted; for it is still narrower a little above and a little below Thermopylae. At Alpini, which is lower down than that place, it is only wide enough for a single carriage; and up above, at the river Phoenix, near the town called Anthela, it is the same. West of Thermopylae rises a lofty and precipitous hill, impossible to climb, which runs up into the chain of Oeta; while to the east the road is shut in by the sea and by marshes. In this place are the warm springs, which the natives call "The Cauldrons"; and above them stands an altar sacred to Hercules.
A wall had once been carried across the opening; and in this there had of old times been a gateway. These works were made by the Phocians, through fear of the Thessalians, at the time when the latter came from Thesprotia to establish themselves in the land of Aeolis, which they still occupy. As the Thessalians strove to reduce Phocis, the Phocians raised the wall to protect themselves, and likewise turned the hot springs upon the pass, that so the ground might be broken up by watercourses, using thus all possible means to hinder the Thessalians from invading their country. The old wall had been built in very remote times; and the greater part of it had gone to decay through age. Now however the Greeks resolved to repair its breaches, and here make their stand against the barbarian. At this point there is a village very nigh the road, Alpeni by name, from which the Greeks reckoned on getting corn for their troops.
These places, therefore, seemed to the Greeks fit for their purpose. Weighing well all that was likely to happen, and considering that in this region the barbarians could make no use of their vast numbers, nor of their cavalry, they resolved to await here the invader of Greece. And when news reached them of the Persians being in Pieria, straightway they broke up from the Isthmus, and proceeded, some on foot to Thermopylae, others by sea to Artemisium.
