treaty with Sparta. But in B.C. 420 Alcibiades, a young and reckless but very able statesman, who now first appears in public business, induced the Athenians to join the Argive confederacy, which, thus strengthened, began warlike operations against other towns in the Peloponnese to compel their adherence; while the Athenians placed escaped helots and Messenians in Pylos with a view of fomenting fresh plundering expeditions upon Spartan territory (B.C. 419). The Spartans could not view these measures with indifference. They declared war on Argos (B.C. 418) and defeated the allied army at Mantinea. Not only was Mantinea compelled to submit, but a revolution took place at Argos itself, which put the oligarchical party in power, which at once made a treaty with Sparta. It is true that next year (B.C. 417) a counter revolution restored the democrats, who rejoined Athens, but the battle of Mantinea practically put an end to efficient opposition to Sparta in the Peloponnese and broke up the conspiracy.
Athens was still nominally at peace with Sparta. But a series of offensive acts on her part led to the open renunciation of that peace. Pylos was a standing ground of quarrel. Athenian troops had fought at Mantinea on the side of Argos; in B.C. 416 an Athenian fleet blockaded the island of Melos (a colony of Sparta) to compel its Dorian inhabitants to be contributors to the Athenian confederacy. At the beginning of the war they had contributed to the Spartan war fund though professing to take neither side.
This had brought upon them an attack from
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