History of the Peloponnesian War

The same winter, after the fleet of the Peloponnesians was dissolved, the Athenians that were at Naupactus under the conduct of Phormio sailed along the coast to Astacus and, disbarking, marched into the inner parts of Acarnania. He had in his army four hundred men of arms that he brought with him in his galleys and four hundred more Messenians. With these he put out of Stratus, Coronta, and other places all those whose fidelity he thought doubtful. And when he had restored Cynes the son of Theolytus to Coronta, they returned again to their galleys.

For they thought they should not be able to make war against the Oeniades (who only of all Acarnania are the Athenians' enemies) in respect of the winter. For the river Achelöus, springing out of the mountain Pindus and running through Dolopia, and through the territories of the Agraeans and the Amphilochians, and through most part of the champaign of Acarnania, passing above by the city of Stratus, and falling into the sea by the city of the Oeniades, which also it moateth about with fens, by the abundance of water maketh it hard lying there for an army in time of winter.