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.
And they gave back the dead, set up a trophy themselves, and took up their own dead, about three hundred in number. They would not, however, openly agree to a retreat for the whole army, but Demosthenes with his Acarnanian colleagues secretly agreed that the Mantineans and Menedaius and the other Peloponnesian commanders and the most influential men among them might go back home, if they did so speedily. Their object was to isolate the Ambraciots and the miscellaneous crowd of mercenaries,[*](Opinions differ as to who are meant. They were probably mercenaries from the neighbouring Epirote tribes in the pay of the Ambraciots.) and above all to discredit the Lacedaemonians and the Peloponnesians with the Hellenes of this region, on the ground that they had committed an act of treachery through preference for their own selfish interests.
Accordingly the Peloponnesians took up their dead and hastily buried them as best they could, while those who had permission began secretly to plan their retreat.
Word was now brought to Demosthenes and the Acarnanians that the inhabitants of the city of Ambracia,[*](As distinguished from the Ambraciots who after the battle were shut up in Olpae (3.111.2).) in response to the first message that came from Olpae, were marching in full force through the Amphilochian territory, wishing to join the forces in Olpae, and that they were quite unaware of what had happened.
So he immediately sent a part of his army to forestall these troops by setting ambuscades along the roads and occupying the strong positions, and at the same time began preparations to lead the rest of the army against them.