The Peloponnesian War was fought between Sparta and Athens from 431 to 404 BC. Sparta’s victory in the Peloponnesian War ended Athens’ dominance in Greece. The war was fought over several decades, with each side gaining and losing ground at various times for a number of reasons. Sparta eventually emerged victorious after destroying Athens’ fleet at Aegospotami, thereby ending its influence on Greek affairs. The war also resulted at the end of Athenian democracy, which had been established just over a century earlier by Cleisthenes.
The Athenians had been a major military power for centuries, but their empire began to decline after they were defeated by Sparta. Though Athens remained an important trading center and cultural center after its defeat, it no longer exerted political influence over other Greek city-states.
Sparta was victorious because it had a stronger military than Athens, which relied on its navy to win battles at sea. And Sparta also benefited from having a more unified government than its rival city-state had; this allowed Sparta to coordinate its efforts more effectively than Athens could do on its own behalf.
Sparta defeated Athens in 431 BC, but the Spartans were then forced to withdraw their troops from Attica due to an uprising within their own city-state. This allowed Athens to rebuild its fleet and defeat Sparta at Aegospotami in 405 BC. The Athenian Empire was destroyed during the Peloponnesian War, but its democratic government survived intact.