Acarnania (ăk´ərnā´nēə), region of ancient Greece, between the Achelous River and the Ionian Sea. The chief city was Stratos. The Acarnanians sided with Athens during the Peloponnesian War, and Athens helped Acarnania to uphold its independence against Corinth and Sparta in the 5th cent. BC Later (390–375 BC) Sparta controlled the region. The persistent struggle with the Aetolians cost Acarnania its independence until 231 BC When the Byzantine Empire broke up (1204), Acarnania passed to Epirus and in 1480 to the Turks. In 1832 it became part of Greece.