of an almost imperial position. That she should have taken the lead in the confederacy was the natural result of her great services in the Persian war; and that she was strong enough to seize the opportunity was owing, above all, to the brilliant abilities of Themistocles, and the high character of Aristides. To Themistocles it was chiefly due that she had become a strong naval power; it was due to his sagacity and gallantry that she had played so important a part in repelling the Persian invasion and to his vigorous exertions that, after that event, she had become a fortified town, with harbours suitable for her expanding trade and growing power. It was at his suggestion in B.C. 477 that the city walls were hastily constructed in spite of the jealous remonstrances of Sparta, and that the Piraeus was also encircled for a distance of seven miles, by the immense double wall which secured it for more than three centuries. And when the policy of Themistocles in exacting contributions from the islands, as a penalty for their involuntary medizing, seemed likely to discredit the state in the eyes of the Greeks, it was the moderation and equity of Aristides that renewed public confidence in its leadership, and caused it to be regarded as the natural head of the new confederacy. This was confirmed by the voluntary withdrawal of the Spartans, who, content with an acknowledged primacy in the Peloponnese and in land warfare generally, allowed the maritime leadership to fall into the hands of Athens, apparently at first without foreseeing the consequences. When, again, the confederacy, after thirteen years
