(2) To make fleet and army act in co-operation, and, furthermore, by means of the fleet, to maintain the command of the Ægean and its sea-ways.
On the side of the defence no plans of such magnitude are apparent; for the very good reason that the preparations to meet the invader were made too late for the carrying out of any far-reaching design, even had so composite a resisting force admitted of anything of the kind.
THESSALY AND THERMOPYLÆ.
The first strategic action of the Greeks was the expedition to North Thessaly. That was undoubtedly conscious strategy. It was undertaken under the supposition that the Vale of Tempe was the only entrance into the country; and had this supposition been correct the strategy was sound enough. The mistake made was topographical, not strategical.
It was again sound strategy which made the Greeks, when they discovered their error, retire from a position which was indefensible with the numbers present with them. Even had their available force been much larger than it actually was, it would have been a mistake to try to defend a mountain line traversed by several passages. A successful attempt of that nature is rare in history, because the assailant is able to choose the passage on which his main attack shall be directed, whereas the defender has to distribute his force at all the possible points of assault. Moreover, the passage once forced, the assailant can generally threaten the lines of communication of the bodies of troops defending the other passes.
Thermopylæ and Artemisium display most clearly the strategy of the two contending sides. It did not perhaps demand much knowledge or much intelligence to fix upon Thermopylæ as a point of defence. It would be difficult to mention any other great highway in the world on which a defensive position so strong by nature is afforded. It was, on the other hand, a great strategic blunder on the part of Sparta that, having sent a small force to the pass, she did not later forward reinforcements. That was no doubt part of a still greater strategic blunder,—the desire to concentrate the defence at the Isthmus. The three days’ fighting at Thermopylæ proved conclusively that, had an adequate force been present there, the army of Xerxes would in all probability never have carried the pass. Sparta and the Peloponnese generally neither did, nor wished to, appreciate the immense strength of the position.
Did the Persians make a mistake in their assault on the pass? It would seem not. They did not at first know of any way of turning it. They had to take it, because it was the only route by which they could get their baggage train past Mount Œta. That is the difficulty of Greek campaigning. There are perhaps many routes in the country along which a light marching force in moderate numbers can make its way; but those by which troops with the ordinary paraphernalia of an army, and in numbers too large to live on the country, can go, are very few.
The Greeks learnt a lesson from their homeland,—a lesson which Xenophon expressed in striking language to the ten thousand Greeks when they began their famous retreat: “My view is that we should burn our waggons, that our baggage train regulate not our march, but we go by whatever way be expedient for the army.”[231] In the present instance Xerxes was confined to the one route: he had to assault the pass, because in the then state of his knowledge of the country he could do nothing else. That he or his generals appreciated the importance of the path of the Anopæa so soon as they were informed of it is shown by the employment of the best troops in the army for its seizure and use.
It is, however, fairly questionable whether the direct assault on the pass formed part of the original Persian design at Thermopylæ. The delay of several days which took place before the actual assault was delivered, taken in connection with the contemporary events at Artemisium, suggests that it was originally intended to wait until the forcing of the Euripus by the fleet made it impossible for the Greeks to maintain their position in the pass for fear of the landing of a force in their rear. If such were the design, it was one which bears testimony to the strategic capacity of him who conceived it. It was brought to nought by a factor outside all human calculation, the storm which broke upon the fleet when anchored at the Sepiad strand.
It was indeed at this period of the war that both the contesting parties gave conspicuous proof of their appreciation of the strategic conditions of the region in which their operations were being carried on. GENIUS AND EXPERIENCE. In point of conception there was little to choose between the plans of the assailant and that of the defender, but in point of execution the Greek plan was wrecked by the deliberate failure of those who were responsible for the land section of the general defence. That of the Persian was upset by causes beyond human control. It is noticeable that the invaders seem to have arrived at Thermopylæ with a fair working knowledge of the region of the Malian gulf and the North Euripus, and it must be suspected that the heralds sent to Greece to demand earth and water acted when there in a twofold capacity.