Acarnania, district of ancient Greece bounded by the Ionian Sea, the Ambracian Gulf, Mount Thyamus, and the Achelous River. Corinth founded several colonies on the coast of Acarnania in the 7th and 6th centuries bc. Originally a tribal unit, Acarnania developed into a federal state with generals and other magistrates, a council, and an assembly by the late 5th century; its capital was at the city of Stratus. With Athenian help, in the early years of the Peloponnesian War it repulsed Corinthian and Spartan attacks and enlarged its territory. In 388 it was compelled by Sparta to give up the Athenian alliance. It later came under Athenian, Theban, and Macedonian rule. In 314 the Acarnanians established a confederation of newly founded cities; but frontier disputes with Aetolia culminated in the partition of their country between Aetolia and Epirus (c. 243). The Epirote part of Acarnania recovered its independence in 231 and set up a new confederacy. By allying with Philip V of Macedon, it succeeded in recovering some of its former territory. When Rome overthrew the Macedonian dynasty (167 bc), it deprived Acarnania of Leucas, the capital of the revived confederacy, and compelled it to send hostages to Rome; but the confederacy, with its capital at Thyrrheum, survived until the Roman emperor Augustus incorporated many Acarnanians into his new city, Nicopolis Actia; the rest were included in the province of Achaea.
In modern Greece, Acarnania is linked with Aetolia in the nomós (department) Aitolía kai Akarnanía.