The Aetolian League was a confederation in ancient Greece centering on the cities of Aetolia in central Greece. The league was established in 370 BC in opposition to Macedon and the Achaean League. It occupied Delphi from 290 BC and gained territory steadily until, by the end of the 3rd century BC, it controlled the whole of central Greece outside Attica. At its height, the league's territory included Locris, Malis, Dolopes, part of Thessaly, Phocis, and Acarnania.
The Aetolians were not highly regarded by other Greeks, who considered them as being almost semi-barbaric. However, their league had a complex political and administrative structure, and their armies were easily a match for the other Greek powers. The league had a federal structure consisting of a federal council in which the level of representation was proportional to the size of a community's contribution to the league's army, a popular assembly of all citizens which met twice a year, and an inner council equivalent to a federal government. It could raise armies and conduct foreign policy on a common basis. It also implemented economic standardisation, levying taxes, using a common currency and adopting a uniform system of weights and measures.
The league was the first Greek ally of the Roman Republic, siding with the Romans during the First Macedonian War, and helping to defeat Philip V of Macedon at the Battle of Cynoscephalae in 197 BC, during the Second Macedonian War. However, it grew increasingly hostile to Roman involvement in Greek affairs and only a few years later sided with Antiochus III, the anti-Roman king of Syria. The defeat of Antiochus in 189 BC robbed the league of its principal foreign ally and made it inviable to stand alone in continued opposition to Rome. The league was forced to sign a peace treaty with Rome that made it a subject ally of the republic. Although it continued to exist in name, the power of the league was broken by the treaty and it never again constituted a significant political or military force.
- Krzysztof Kęciek "Kynoskefalaj 197 p.n.e" Serie Historic Battles Published in Warsaw by Bellona in 2002