The Peloponnesian War was fought between two prominent city-states of ancient Greece: Athens and Sparta. Athens was a powerful naval state and known for its democratic government, while Sparta was a militaristic state with a strong land-based army. The war lasted from 431 BCE to 404 BCE and had a profound impact on the Greek world. It began as a conflict between the Delian League, led by Athens, and the Peloponnesian League, led by Sparta, but gradually drew in other Greek city-states and regional powers. Ultimately, Sparta emerged as the victor and Athens' dominance was diminished.