In antiquity, the city of Naupactus on the Gulf of Corinth belonged to the Ozolian Locrians. Later it became the capital of Aetolia and was an important political and military centre in the Aeolian League. In 146 BC, it was conquered by the Romans, and under Byzantium it was the seat of a bishop. In 1210, Naupactus was incorporated into the Despotate of Eripus, and in 1403 it was sold to the Venetians. In 1499 the Turks took it, and their occupation lasted until 1829 with a brief period of Venetian rule from 1687 to 1700. naupactus was the scene, in 1571, of the Battle of Lepanto between the Turks and the united fleets of Venice, Spain and Pope Pius V. the defeat of the Ottoman Empire in that battle marked the beginning of the collapse of its sea power.
Modern Nafpactos is a tourist resort with many interesting sights, including the fine Venetian castle, which has survived in quite good condition, and the harbour with its Venetian towers and bastions.