The Peace of Nicias and the Sicilian Expedition

"The Peloponnesian War (431-404 BC) was an ancient Greek war fought by Athens and its empire against the Peloponnesian League led by Sparta....the Spartan general Brasidas raised an army of allies and helots and marched the length of Greece to the Athenian colony of Amphipolis in Thrace, which controlled several nearby silver mines; their product supplied much of the Athenian war fund. Thucydides was dispatched with a force which arrived too late to stop Brasidas capturing Amphipolis; Thucydides was exiled for this, and, as a result, had the conversations with both sides of the war which inspired him to record its history. Both Brasidas and Cleon were killed in Athenian efforts to retake Amphipolis (see Battle of Amphipolis). The Spartans and Athenians agreed to exchange the hostages for the towns captured by Brasidas, and signed a truce....With the death of Cleon and Brasidas, zealous war hawks for both nations, the Peace of Nicias was able to last for some six years."--Wikipedia.

"The Sicilian Expedition was an Athenian expedition to Sicily from 415 BC to 413 BC, during the Peloponnesian War.... nearly the entire expedition surrendered or was destroyed in the Sicilian interior. The impact of the defeat was immense. Two hundred ships and thousands of soldiers, an appreciable portion of the city's total manpower, were lost in a single stroke. Athens' enemies on the mainland and in Persia were encouraged to take action, and rebellions broke out in the Aegean. The defeat proved to be the crucial turning point in the Peloponnesian War, though Athens struggled on for another decade."--Wikipedia.