While the Athenians were encamped at the sacred precinct of Herakles, they were joined by a contingent from the Bœotian town of Platæa. Some twenty-nine years before this time the Athenians had taken the little city under their protection against its formidable neighbour Thebes, which had tried to force it to become a member of the Bœotian confederacy. It was out of gratitude for the aid then given, and for the protection afterwards extended to them, that the Platæans now shared the perils of their benefactors. While the Athenian position at Marathon is clearly determined by the identification of the precinct of Herakles, the station taken up by the Persian army must remain a matter of uncertainty. No topographical detail by which it can be identified has survived. The “Soros” shows, indeed, where the actual fight took place; but it does _not_ define the position of the Persian army during the days of waiting before the battle was fought. The only detail preserved in the various traditions of the battle which can be said to cast any light on the position of the original encampment of the Persian force is that the Persian fleet was “anchored” at Marathon, not drawn up on shore.[76] The truth of the detail is rendered probable by the general history of events, in which it is conspicuously shown that the Persian design demanded that a portion, at least, of their fleet should be ready to start at a moment’s notice. Except at the northern end, where the promontory of Kynosura forms a natural breakwater, the bay of Marathon is open and exposed. As an anchorage for vessels the northern end would naturally be chosen. It may be presumed that the army would be encamped in the immediate neighbourhood of the fleet; and, if so, its original position must have been north of the Charadra, hidden from the Greek encampment by the rise of the modern Mount Kotroni. Doubtless both sides had outposts in view of the enemy’s camp. ◆H. vi. 109.◆