Agrinium had the misfortune to find itself embroiled in the struggle for supremacy between the Macedonians (under Cassander) and the Aetolians. The latter were engaged in a perennial conflict with the Acarnanians, who lived on the far (western) shores of the river Achelous. In 314 BCE the Macedonians moved into Aetolia but only as a diversion, since their real target was Leucas and other cities along the Adriatic shore. Cassander made a show of force but soon departed, leaving behind a relatively small garrison entrusted with the task to assist the Acarnanians, should the Aetolians decide to move against them. And move they did, for they were determined to eliminate all enemy strongholds.