History of the Peloponnesian War

Demosthenes and the Acarnanians had now intelligence that the Ambraciotes from the city of Ambracia, according to the message sent to them before from Olpae [which was that they should bring their whole power through Amphilochia to their aid], were already on their march (ignorant of what had passed here) to join with those at Olpae.

And hereupon he sent a part of his army presently forth to beset the ways with ambushment and to pre-occupy all places of strength, and prepared withal to encounter with the rest of his army.