The Ambracians, who were allies of the Spartans, had sent a relief force to help the army that had invaded Amphilochia previously.
Unbeknownst to the Ambracians, the first army had been defeated, surrounded and scattered by the allied Athenians, Amphilochians and Acarnanians the day before.
The Ambracians, unaware of the incoming Athenian army, camped on the lower of two steep hills.
Demosthenes, the Athenian commander, occupied the higher hill, obtaining a strategic advantage.
Thucydides describes this disaster: "Indeed, this was by far the greatest disaster that befell any one Hellenic city in an equal number of days during this war; and I have not set down the number of the dead, because the amount stated seems so out of proportion to the size of the city as to be incredible".