The outcome of the Peloponnesian War was the victory of Sparta over Athens, significantly altering the balance of power in ancient Greece. This protracted conflict, which lasted from 431 to 404 BC, resulted in the decline of Athenian naval dominance and political influence. Sparta's coalition of city-states, known as the Peloponnesian League, successfully besieged Athens, leading to its surrender. The war had devastating consequences, including widespread destruction and loss of life, and it ultimately weakened the Greek city-states, paving the way for future conflicts, including the rise of Philip II of Macedon and, later, the conquests of Alexander the Great.