History of the Peloponnesian War

The Ambraciots at Olpae also sent a messenger to their city, desiring them to come in full force to their assistance, fearing that the troops under Eurylochus might not be able to effect a passage through the Acarnanians, and that they themselves might either have to fight unsupported, or, if they wished to retreat, find it unsafe to do so.

The Peloponnesians with Eurylochus, therefore, finding that the Ambraciots at Olpae were come, set out from Proschium and went as quickly as possible to their aid; and having crossed the Acheloüs, proceeded through Acarnania, which was left deserted in consequence of the reinforcement sent to Argos; keeping on their right hand the city of the Stratians with their garrison, and on the left the rest of Acarnania.

After passing the territory of the Stratians, they proceeded through Phytia, and again through Medeon, along the borders; then through Limnaea; and so they entered the territory of the $Aegraeans, which formed no part of Acarnania, but was friendly to themselves.

Then, having reached Mount Thyamus, which is uncultivated, they proceeded across it, and so came down into the Argive country by night, and passing unobserved between the city of Argos and the Acarnanian posts at Crenae, joined the Ambraciots at Olpae.