History of the Peloponnesian War

The Potidaeans and the Peloponnesians under Aristeus were awaiting the Athenians, encamped on the Olynthian side of the isthmus; and they had established a market outside of the city.

The allies had chosen Aristeus general of all the infantry, and Perdiccas of the cavalry; for Perdiccas had immediately deserted the Athenians again[*](For his first desertion of the Athenians, see Thuc. 1.57.) and was now in alliance with the Potidaeans, having appointed Iolaus as his administrator at home.

The plan of Aristeus was as follows: he was to hold his own army on the isthmus and watch for the approach of the Athenians, while the Chalcidians and the other allies from outside of the isthmus[*](i.e. the Bottiaeans, who, like the Chalcidians, lived outside the isthmus.) and the two hundred horse furnished by Perdiccas were to remain at Olynthus; then when the Athenians should move against the forces of Aristeus, the others were to come up and attack them in the rear, and thus place the enemy between their two divisions.

But Callias, the commander of the Athenians, and his colleagues sent the Macedonian cavalry and a few of the allies toward Olynthus, to shut off aid from that quarter, while they themselves broke camp and advanced against Potidaea.

And when they arrived at the isthmus and saw the enemy preparing for battle, they took up their position facing them and soon the two sides joined battle.

And the wing led by Aristeus himself, which included the picked Corinthian and other troops, routed the forces opposed to them and pressed on a long distance in pursuit; but the rest of the army of the Potidaeans and the Peloponnesians was worsted by the Athenians and took refuge within the walls of Potidaea.