This war had not been brought to a termination, when, in the year 465 B.C., a tremendous earthquake destroyed Sparta, and a sudden ruin threatened to overwhelm the chief state of Greece. For, in the hope of utterly annihilating their rulers, many helots revolted, and the war was called the Third Messenian War. Upon this the Lacedæmonians, foreseeing a tedious siege, called in the aid of their allies; and this call was answered among others by the Athenians; the Spartans, however, dismissed them, as we have seen, before the fortress was taken. Immediately after the dismission of the Athenians from Ithome, the injured people of Athens annulled the alliance with Sparta, which had subsisted since the Persian War. Then followed the war with the maritime towns of Argolis, in which Athens, after many reverses, at length succeeded in destroying the fleet of Ægina, and subjugating that island (457 B.C.). The inactivity of Sparta during these astonishing successes of her enemy (for when she concluded the armistice with Athens she must have partly foreseen its consequences) seems to prove that she was entirely occupied with the final capture of Ithome, and the settlement of her interests in Arcadia. The five years’ truce in 451 B.C. was only an armistice between Athens and the Peloponnesian confederacy, which left Bœotia to shake off the Athenian yoke by her own exertions. At the end of these five years Megara revolted from the Athenians, and in consequence an invasion of Attica by the Peloponnesians took place, which, though it did not produce any immediate result, was soon followed by the Thirty Years’ Truce, in which Athens ceded her conquests in Megaris and the Peloponnese, and on the mainland returned within her ancient boundaries. If now we consider the events which have been briefly traced it will be perceived, that the principle on which the Lacedæmonians constantly acted was one of self-defence, of restoring what had been lost, or preserving what was threatened with danger; whereas the Athenians were always aiming at attack or conquest, or the change of existing institutions. While the Spartans during this period, even after the greatest victories, did not conquer a foot of land, subjugate one independent state, or destroy one existing institution; the Athenians, for a longer or for a shorter time, reduced large tracts of country under their dominion, extended their alliance (as it was called) on all sides, and respected no connection when it came in conflict with their plans of empire.