The Peloponnesian War in Greece lasted for over twenty years, 431 – 404 B.C. The war was between the city states of Athens and Sparta. The eventual victor was Sparta.
Sparta gathered its allies, called the Peloponnesian League, when it began to feel threatened by Athenian Imperialism. Because Sparta had the strongest army they felt quite sure of victory.
Athens’ allies, the Delian League, gathered in response and began to create a huge navy. But in 430 B.C. a plague swept through Athens and killed over two-thirds of the population. This huge setback demoralized the Athenians completely.
After ten years of fighting a stalemate was reached in 421 B.C. for the time span of six years. But during those years, skirmishes still occurred among the allies of both Athens and Sparta.
During this temporary time of peace, the Athenians went on an expedition to Sicily. Under the pretense of helping Sicily as an ally in need, they tried to conquer them. However, the Athenians lost 50,000 men and failed to capture Sicily. This immense loss was the eventual cause for their surrender to Sparta.
After a naval battle in 405 B.C., which resulted in a Spartan victory under the general Lysander, the Athenians surrendered in 404 B.C., faced with a severe threat of starvation.