History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
For it seemed impracticable in winter to make a campaign against Oeniadae, whose inhabitants alone of the Acarnanians were always hostile; for the river Achelous, which rises in Mount Pindus and flows through the country of the Dolopians, Agraeans, and Amphilochians and then through the Acarnanian plain, passes by the city of Stratus high up the stream, but by Oeniadae empties into the sea, where it surrounds the city with marshes, thus rendering military operations there impossible in winter by reason of the water.
Besides, most of the Echinades islands lie opposite to Oeniadae at no great distance from the mouths of the Achelous, so that the river, which is large, keeps making fresh deposits of silt, and some of the islands have already become part of the mainland, and probably this will happen to all of them in no great while.
For the stream is wide and deep and turbid, and the islands are close together and serve to bind to one another the bars as they are formed, preventing them from being broken up, since the islands lie, not in line, but irregularly, and do not allow straight channels for the water into the open sea. These islands are uninhabited and not large.
There is a story that when Alemaeon son of Amphiaraus was a wanderer after the murder of his mother,[*](Eriphyle.) Apollo directed him by oracle to inhabit this land, intimating that he would have no release from his fears until he should find and settle in a country which at the time he killed his mother had not yet been seen by the sun, and was not even land then, for all the rest of the earth had been polluted by him.
And he, in his perplexity, at last, as the story goes, observed this sand-bar formed by the Achelous, and he surmised that during the long time he had been wandering since he had slain his mother enough land would have been silted up to support life in. So he settled there in the region of Oeniadae, founded a principality, and left to the country its name Acarnania, after that of his son Acarnan. Such is the tradition which we have received concerning Alcmaeon.
The Athenians and Phormio set out from Acarnania and arrived at Naupactus, and later, at the beginning of spring, sailed back to Athens, bringing with them the captured ships and also the prisoners of free birth whom they had taken in the sea-fights. These were exchanged man for man.