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.
The Athenians in the twenty ships also departed, returning to Naupactus. As for the Acarnanians and Amphilochians, after the Athenians and Demosthenes had gone home, they concluded a truce with the Ambraciots and Peloponnesians who had taken refuge with Salynthius and the Agraeans, allowing them to withdraw from Oeniadae, whither they had gone after leaving Salynthius.
The Acarnanians and Amphilochians also concluded for the future a treaty of alliance with the Ambraciots to last for one hundred years, on the following terms: The Ambraciots were not to join the Acarnanians in any expedition against the Peloponnesians; nor were the Acarnanians to join the Ambraciots against the Athenians, but they were to give aid in defence of one another's territory; the Ambraciots were to restore all places or hostages belonging to the Amphilochians which they now held; and they were not to give aid to Anactorium, which was hostile to the Acarnanians.
On these terms of agreement they brought the war to an end. But after this the Corinthians sent to Ambracia a garrison of their own troops, consisting of about three hundred hoplites, under the command of Xenocleidas son of Euthycles, who, making their way with difficulty across he mainland, finally reached their destination. Such was the course of events at Ambracia.
During the same winter the Athenians in Sicily made a descent from their ships upon the territory of Himera, in concert with the Sicels from the interior who had invaded the extreme border[*](ie. toward the interior.) of Himeraea; and they also sailed against the islands of Aeolus.