In the latter part of its power, certain Greek city-states joined the Aetolian League such as the Arcadian cities of Mantineia, Tegea, Phigalia and Kydonia on Crete.

However, during the Hellenistic period, they emerged as a dominant state in central Greece and expanded by the voluntary annexation of several Greek city-states to the League.

Still, the Aetolian League had to fight against Macedonia and were driven to an alliance with Rome, which resulted in the final conquest of Greece by the Romans.

After the death of Philip II in 336 BC, the Aetolians joined the Thebans in opposing Alexander the Great and the stress of their defeat caused the league to implode.

Demetrius Poliorcetes launched the Fifth Sacred War, 289-287 BC, in an attempt to remove them, but was defeated and driven from Macedonia altogether with the help of Pyrrhus of Epirus.

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 the Seleucid Empire, during the Roman-Syrian War.

The defeat of Antiochus in 189 BC robbed the league of its principal foreign ally and made it impossible to stand alone in continued opposition to Rome.

It also implemented economic standardization, levying taxes, using a common currency and adopting a uniform system of weights and measures.

The assembly was the ultimate authority within the league, with responsibility for declarations of war and peace, but its power was limited by the infrequency with which it met.

A small portion of the council's members, known as the apokletoi ("Select-men"), conducted day-to-day business, such as sending and receiving embassies.

The chief executive was the strategos (General), who commanded the league's armies, received all diplomatic contacts from other states in first instance, and presided over meetings of the assembly, the council, and the select-men.

The hipparchos (Cavalry Commander), originally a minor post, became the General's deputy from the late 260s BC, but his exact responsibilities are not clear.

For example, Walbank is explicit in seeing the Aetolians as systematically using piracy to supplement their income due to the meager resources of their region[15] and Will simply assumes the truth of the charge.