Now that they had again become allies of Argos, the Athenians probably found out, more fully than they had before known, the intrigue carried on by the former Argeian government with the Macedonian Perdikkas. The effects of these intrigues, however, had made themselves felt even earlier in the conduct of that prince, who, having as an ally of Athens engaged to coöperate with an Athenian expedition projected under Nikias for the spring or summer of 417 B.C. against the Chalkidians of Thrace and Amphipolis, now withdrew his concurrence, receded from the alliance of Athens, and frustrated the whole scheme of expedition. The Athenians accordingly placed the ports of Macedonia under naval blockade, proclaiming Perdikkas an enemy.[155] [155] Thucyd. v, 83. Nearly five years had elapsed since the defeat of Kleon, without any fresh attempt to recover Amphipolis: the project just alluded to appears to have been the first. The proceedings of the Athenians with regard to this important town afford ample proof of that want of wisdom on the part of their leading men Nikias and Alkibiades, and of erroneous tendencies on the part of the body of the citizens, which we shall gradually find conducting their empire to ruin. Among all their possessions out of Attica, there was none so valuable as Amphipolis: the centre of a great commercial and mining region, situated on a large river and lake which the Athenian navy could readily command, and claimed by them with reasonable justice, since it was their original colony, planted by their wisest statesman, Periklês. It had been lost only through unpardonable negligence on the part of their generals; and when lost, we should have expected to see the chief energies of Athens directed to the recovery of it; the more so, as, if once recovered, it admitted of being made sure and retained as a future possession. Kleon is the only leading man who at once proclaims to his countrymen the important truth that it never can be recovered except by force. He strenuously urges his countrymen to make the requisite military effort, and prevails upon them in part to do so, but the attempt disgracefully fails; partly through his own incompetence as commander, whether his undertaking of that duty was a matter of choice or of constraint, partly through the strong opposition and antipathy against him from so large a portion of his fellow-citizens, which rendered the military force not hearty in the enterprise. Next, Nikias, Lachês, and Alkibiadês, all concur in making peace and alliance with the Lacedæmonians, with express promise and purpose to procure the restoration of Amphipolis. But after a series of diplomatic proceedings, which display as much silly credulity in Nikias as selfish deceit in Alkibiadês, the result becomes evident, as Kleon had insisted, that peace will not restore to them Amphipolis, and that it can only be regained by force. The fatal defect of Nikias is now conspicuously seen: his inertness