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.
In this manner, then, the Ambraciots suffered disaster, and but few out of many returned in safety to their city; the Acarnanians, on the other hand, after stripping the dead and setting up trophies, returned to Argos.
On the next day a herald came to the Athenians from the Ambraciots who had escaped from Olpae and taken refuge among the Agraeans, to ask for the bodies of those who had been slain after the first battle, at the time when unprotected by a truce these attempted to leave Olpae along with the Mantineans and the others who were included in the truce.
Now when the herald saw the arms taken from the Ambraciots who came from the city, he was amazed at their number; for he did not know of the recent disaster, but thought that the arms belonged to the men of his own division.
And someone asked him why he was amazed, and how many of his comrades had been slain, the questioner on his part supposing that the herald had come from the forces which had fought at Idomene.