Mantineia.—Oligarchical conspiracy of the Thousand-regiment at Argos, in concert with the Lacedæmonians.—Treaty of peace between Sparta and Argos.—Treaty of alliance between Sparta and Argos—dissolution of the alliance of Argos with Athens, Mantineia, and Elis.—Submission of Mantineia to Sparta.—Oligarchical revolution effected at Argos by the Thousand, in concert with the Lacedæmonians.—Oligarchy in Sikyôn and the towns in Achaia.—Violences of the Thousand at Argos: counter-revolution in that town: restoration of the democracy.—Proceedings of the restored Argeian Demos: tardiness of Sparta.—Alkibiadês at Argos: measures for the protection of the democracy.—Nominal peace, but precarious relations, between Athens and Sparta.—Relations of Athens with Perdikkas of Macedonia.—Negligence of Athens about Amphipolis: improvidence of Nikias and the peace-party: adventurous speculations of Alkibiadês.—Projected contention of ostracism between Nikias and Alkibiadês. Proposition supported by Hyperbolus.—Gradual desuetude of the ostracism, as the democracy became assured.—Siege of Mêlos by the Athenians.—Dialogue set forth by Thucydidês, between the Athenian envoys and the Executive Council of Mêlos.—Language represented by Thucydidês as having been held by the Athenian envoys—with the replies of the Melians.—Refusal of the Melians to submit.—Siege and capture of Mêlos.—Remarks upon the event.—View taken by Thucydidês of this incident.—Place which it occupies in the general historical conception of Thucydidês. 61-118 CHAPTER LVII. SICILIAN AFFAIRS AFTER THE EXTINCTION OF THE GELONIAN DYNASTY.