The next day the thirty Athenian vessels put out to sea, accompanied by all the Corcyraean ships that were seaworthy, and sailed to the harbour at Sybota, where the Corinthians lay, to see if they would engage. The Corinthians put out from the land and formed a line in the open sea, but beyond this made no further movement, having no intention of assuming the offensive. For they saw reinforcements arrived fresh from Athens, and themselves confronted by numerous difficulties, such as the necessity of guarding the prisoners whom they had on board and the want of all means of refitting their ships in a desert place. What they were thinking more about was how their voyage home was to be effected; they feared that the Athenians might consider that the treaty was dissolved by the collision which had occurred, and forbid their departure.
Accordingly they resolved to put some men on board a boat, and send them without a herald's wand to the Athenians, as an experiment. Having done so, they spoke as follows: "You do wrong, Athenians, to begin war and break the treaty. Engaged in chastising our enemies, we find you placing yourselves in our path in arms against us. Now if your intentions are to prevent us sailing to Corcyra, or anywhere else that we may wish, and if you are for breaking the treaty, first take us that are here and treat us as enemies." Such was what they said, and all the Corcyraean armament that were within hearing immediately called out to take them and kill them. But the Athenians answered as follows: "Neither are we beginning war, Peloponnesians, nor are we breaking the treaty; but these Corcyraeans are our allies, and we are come to help them. So if you want to sail anywhere else, we place no obstacle in your way;but if you are going to sail against Corcyra, or any of her possessions, we shall do our best to stop you."Receiving this answer from the Athenians, the Corinthians commenced preparations for their voyage home, and set up a trophy in Sybota, on the continent; while the Corcyraeans took up the wrecks and dead that had been carried out to them by the current, and by a wind which rose in the night and scattered them in all directions, and set up their trophy in Sybota, on the island, as victors. The reasons each side had for claiming the victory were these. The Corinthians had been victorious in the sea-fight until night; and having thus been enabled to carry off most wrecks and dead, they were in possession of no fewer than a thousand prisoners of war, and had sunk close upon seventy vessels. The Corcyraeans had destroyed about thirty ships, and after the arrival of the Athenians had taken up the wrecks and dead on their side; they had besides seen the Corinthians retire before them, backing water on sight of the Athenian vessels, and upon the arrival of the Athenians refuse to sail out against them from Sybota. Thus both sides claimed the victory.
The Corinthians on the voyage home took Anactorium, which stands at the mouth of the Ambracian gulf. The place was taken by treachery, being common ground to the Corcyraeans and Corinthians.
After establishing Corinthian settlers there, they retired home. Eight hundred of the Corcyraeans were slaves; these they sold; two hundred and fifty they retained in captivity, and treated with great attention, in the hope that they might bring over their country to Corinth on their return; most of them being, as it happened, men of very high position in Corcyra. In this way Corcyra maintained her political existence in the war with Corinth, and the Athenian vessels left the island. This was the first cause of the war that Corinth had against the Athenians, viz., that they had fought against them with the Corcyraeans in time of treaty.
Almost immediately after this, fresh differences arose between the Athenians and Peloponnesians, and contributed their share to the war. Corinth was forming schemes for retaliation, and Athens suspected her hostility. The Potidaeans, who inhabit the isthmus of Pallene, being a Corinthian colony, but tributary allies of Athens, were ordered to raze the wall looking towards Pallene, to give hostages, to dismiss the Corinthian magistrates, and in future not to receive the persons sent from Corinth annually to succeed them. It was feared that they might be persuaded by Perdiccas and the Corinthians to revolt, and might draw the rest of the allies in the direction of Thrace to revolt with them. These precautions against the Potidaeans were taken by the Athenians immediately after the battle at Corcyra. Not only was Corinth at length openly hostile, but Perdiccas, son of Alexander, king of the Macedonians, had from an old friend and ally been made an enemy. He had been made an enemy by the Athenians entering into alliance with his brother Philip and Derdas, who were in league against him. In his alarm he had sent to Lacedaemon to try and involve the Athenians in a war with the Peloponnesians, and was endeavouring to win over Corinth in order to bring about the revolt of Potidaea. He also made overtures to the Chalcidians in the direction of Thrace, and to the Bottiaeans, to persuade them to join in the revolt; for he thought that if these places on the border could be made his allies, it would be easier to carry on the war with their co-operation. Alive to all this, and wishing to anticipate the revolt of the cities, the Athenians acted as follows. They were just then sending off thirty ships and a thousand heavy infantry for his country under the command of Archestratus, son of Lycomedes, with four colleagues. They instructed the captains to take hostages of the Potidaeans, to raze the wall, and to be on their guard against the revolt of the neighbouring cities.