The Athenians, on their return to Attica, after the defeat of the Persians, found their city ruined and their country desolate. They began to rebuild their city on a larger scale than before, and to fortify it with a wall. Those allies to whom the increasing maritime power of Athens was an object of suspicion, and especially the AEginetans, to whom it was more particularly formidable, beheld her rising fortifications with dismay. They endeavoured to inspire the Lacedaemonians with their fears, and urged them to arrest the work. But though Sparta shared the jealousy of the allies, she could not with any decency interfere by force to prevent a friendly city from exercising a right inherent in all independent states. She assumed therefore the hypocritical garb of an adviser and counsellor. Concealing her jealousy under the pretence of zeal for the common interests of Greece, she represented to the Athenians that, in the event of another Persian invasion, fortified towns would serve the enemy for camps and strongholds, as Thebes had done in the last war; and proposed that the Athenians should not only desist from completing their own fortifications, but help to demolish those which already existed in other towns. The object of the proposal was too transparent to deceive so acute a statesman as Themistocles. Athens was not yet, however, in a condition to incur the danger of openly rejecting it; and he therefore advised the Athenians to dismiss the Spartan envoys with the assurance that they would send ambassadors to Sparta to explain their views. He then caused himself to be appointed one of these ambassadors; and setting off straightway for Sparta, directed his colleagues to linger behind as long as possible. At Sparta, the absence of his colleagues, at which he affected to be surprised, afforded him an excuse for not demanding an audience of the ephors. During the interval thus gained, the whole population of Athens, of both sexes and every age, worked day and night at the walls, which, when the other ambassadors at length arrived at Sparta, had attained a height sufficient to afford a tolerable defence. Meanwhile the suspicions of the Spartans had been more than once aroused by messages from the AEginetans respecting the progress of the walls. Themistocles, however, positively denied their statements; and urged the Spartans to send messengers of their own to Athens in order to learn the true state of affairs, at the same time instructing the Athenians to detain them as hostages for the safety of himself and colleagues. When there was no longer any motive for concealment, Themistocles openly avowed the progress of the works, and his intention of securing the independence of Athens, and enabling her to act for herself. The walls being now too far advanced to be easily taken, the Spartans found themselves compelled to acquiesce, and the works were completed without further hindrance.