Pel ‧ o ‧ pon ‧ ne ‧ sian War, the /ˌpeləpəniːʃ ə n ˈwɔːʳ/ BrE AmE
(431–404BC) a long war between the ancient Greek states of Athens and Sparta. It ended with the defeat of Athens, and this led to the end of Athens’ political power in ancient Greece. The history of the war by the ancient Greek writer Thucydides is one of the most famous European works of history.