History of the Peloponnesian War

The Athenians also immediately received the news of the revolt of the cities. On being informed that Aristeus and his reinforcements were on their way, they sent two thousand heavy infantry of their own citizens and forty ships against the places in revolt, under the command of Callias, son of Calliades, and four colleagues.

They arrived in Macedonia first, and found the force of a thousand men that had been first sent out, just become masters of Therme and besieging Pydna.

Accordingly they also joined in the investment, and besieged Pydna for a while. Subsequently they came to terms and concluded a forced alliance with Perdiccas, hastened by the calls of Potidaea, and by the arrival of Aristeus at that place. They withdrew from Macedonia,

going to Beroea and thence to Strepsa, and, after a futile attempt on the latter place, they pursued by land their march to Potidaea with three thousand heavy infantry of their own citizens, besides a number of their allies, and six hundred Macedonian horsemen, the followers of Philip and Pausanias. With these sailed seventy ships along the coast.

Advancing by short marches, on the third day they arrived at Gigonus, where they encamped.