History of the Peloponnesian War

When the battles were in order on either side, they came to blows. Demosthenes, with the Messenians and those few Athenians that were there, stood in the right wing; and the Acarnanians (as they could one after another be put in order) and those Amphilochian darters which were present, made up the other. The Peloponnesians and Ambraciotes were ranged promiscuously, except only the Mantineans, who stood together most of them in the left wing, but not in the utmost part of it; for Eurylochus and those that were with him made the extremity of the left wing, against Demosthenes and the Messenians.

When they were in fight, and that the Peloponnesians with that wing overreached and had encircled the right wing of their enemies, those Acarnanians that lay in ambush, coming in at their backs, charged them and put them to flight in such sort as they endured not the first brunt, and besides, caused the greatest part of the army through affright to run away. For when they saw that part of it defeated which was with Eurylochus, which was the best of their army, they were a great deal the more afraid. And the Messenians that were in that part of the army with Demosthenes, pursuing them, dispatched the greatest part of the execution.

But the Ambraciotes that were in the right wing, on that part had the victory, and chased the enemy unto the city of Argos.