History of the Peloponnesian War

And Aristeus, when he came back from the execution, was in doubt what way to take, to Olynthus or to Potidaea. In the end he resolved of the shortest way, and with his soldiers about him ran as hard as he was able into Potidaea, and with much ado got in at the pier through the sea, cruelly shot at and with the loss of a few but the safety of the greatest part of his company.

As soon as the battle began, they that should have seconded the Potidaeans from Olynthus (for it is at most but sixty furlongs off, and in sight) advanced a little way to have aided them; and the Macedonian horse opposed themselves likewise in order of battle to keep them back. But the Athenians having quickly gotten the victory, and the standards being taken down, they retired again, they of Olynthus into that city, and the Macedonian horsemen into the army of the Athenians. So that neither side had their cavalry at the battle.

After the battle the Athenians erected a trophy and gave truce to the Potidaeans for the taking up of the bodies of their dead. Of the Potidaeans and their friends there died somewhat less than three hundred, and of the Athenians themselves one hundred and fifty, with Callias one of their commanders.

Presently upon this the Athenians raised a wall before the city on the part toward the isthmus which they kept with a garrison, but the part to Pallene-ward they left unwalled. For they thought themselves too small a number both to keep a guard in the isthmus and withal to go over and fortify in Pallene, fearing lest the Potidaeans and their confederates should assault them when divided.

When the people of Athens understood that Potidaea was unwalled on the part toward Pallene, not long after they sent thither sixteen hundred men of arms under the conduct of Phormio the son of Asopius, who arriving in Pallene left his galleys at Aphytis, and marching easily to Potidaea wasted the territory as he passed through. And when none came out to give him battle, he raised a wall before the city on that part also that looketh towards Pallene.

Thus was Potidaea on both sides strongly besieged, and also from the sea by the Athenian galleys that came up and rode before it.