History of the Peloponnesian War

When both sides were ready they joined battle; Demosthenes being on the right wing with the Messenians and a few Athenians, while the rest of the line was made up of the different divisions of the Acarnanians, and of the Amphilochian darters. The Peloponnesians and Ambraciots were drawn up pell-mell together, with the exception of the Mantineans, who were massed on the left, without however reaching to the extremity of the wing, where Eurylochus and his men confronted the Messenians and Demosthenes.

The Peloponnesians were now well engaged and with their outflanking wing were upon the point of turning their enemy's right; when the Acarnanians from the ambuscade set upon them from behind, and broke them at the first attack, without their staying to resist; while the panic into which they fell caused the flight of most of their army, terrified beyond measure at seeing the division of Eurylochus and their best troops cut to pieces. Most of the work was done by Demosthenes and his Messenians, who were posted in this part of the field.

Meanwhile the Ambraciots (who are the best soldiers in those countries) and the troops upon the right wing, defeated the division opposed to them and pursued it to Argos.