The Peloponnesian War (431 to 404 B.C.) was fought between the rival Greek city-states of Athens and Sparta for dominance in Greece. The lengthy series of battles was known as the Peloponnesian War in which Sparta and its allies eventually defeated Athens and its allies. It was a crushing defeat for Athens.
The seeds of the Second Peloponnesian War were sown in 434 BC when Epidamnus enlisted aid from Corinth (a Spartan ally) after being denied by her colonial power, Corcyra. Corcyraean outrage over the Corinthian aid led to war, prompting the Corcyraeans to petition Athens’ help.
In 431 B.C. a war erupted between Athens and Sparta and its allies. Athens controlled the sea but Sparta had a strong army, and the irresistible force had met the immovable object. The Spartan military is famous for its tremendous discipline to this day; boys were trained to be great soldiers beginning at age seven and serving the army from ages 20 to 60. The Athenian leader Nicias negotiated the Peace of Nicias (421 B.C.).
But the peace lasted only a few years. Fighting resumed, and Sparta defeated the combined armies of Athens and her allies at Mantinea. In 415 a radical new leader of Athens, Alcibiades, convinced the Athenian Assembly to invade Syracuse, a Peloponnesian ally in Sicily. It was a total disaster. The end was near for Athens, which was weakened further by a plague that killed much of her population. Sparta then had a fleet to challenge Athens on the seas, and benefited from an extraordinary military leader named Lysander. He seized the Hellespont to cut off Athens' grain imports and threaten the city-state with starvation. Athens sent all it had let to confront him, but failed at Aegospotami in 405 B.C.
Faced with bankruptcy, Athens gave up nearly everything just to attain peace. Athens lost her city walls and all of her possessions overseas. She also lost democracy as Sparta’s anti-democratic party took control. Sparta had won the Peloponnesian War.
Democracy rose up again in a few years and in 395 B.C. Sparta removed Lysander from office. In 387 Sparta lost the favor of public opinion by surrendering Greek cities (Ionia and Cyprus) to the enemy Persia, even though Greece had been beating Persia for a hundred years. When Sparta then tried to weaken its former ally Thebes, a battle broke out between them and Athens joined with Thebes to defeat Sparta.
The Greek historian, Thucydides, (c. 460 BC – c. 400 BC), is famous for his history of the Peloponnesian War.