There can be little doubt that Pericles, who was mainly responsible for this decision, committed a fatal error in advising the Athenians to take up the cause of Corcyra. By this act Athens incurred the implacable hostility of Corinth, and revived the old grudge which that city had conceived against her when Megara joined the Athenian alliance. In the constantly shifting currents of Greek politics, Athens might well, under wise guidance, have steered her way safely through the perils which surrounded her. The Corinthians had half forgotten their grievance, as is proved by their conduct at the revolt of Samos; and the tone of their representative at the Corcyraean debate is decidedly friendly. The Spartans were sluggish and procrastinating by nature, and required some powerful impulse to induce them to act with vigour; and this impulse was now supplied by Corinth. By accepting, therefore, the alliance of Corcyra, Athens barred the way to all compromise, and gathered into one head all the scattered causes of jealousy and hatred which had been accumulating against her in the last fifty years. Early in the following year the Corinthian fleet, numbering a hundred and fifty sail, put to sea from Corinth, to renew the war with Corcyra, and a battle was fought off the coast of Epirus. The engagement was long and fierce, and the event was finally decided by a small squadron of Athenian ships, which had been sent with instructions to hinder any attempt of the enemy to land on the island Seeing that the Corcyraeans were being forced back upon their own coast, the Athenian captains, who had hitherto looked on, and taken no part in the battle, now assumed the offensive, and lent such effectual aid that the Corinthians were held in check until the sudden appearance of twenty additional ships from Athens, which had been sent off immediately after the others, put an end to the action. This timely interference saved Corcyra from ruin; for next day the Corinthians, after a formal remonstrance, set sail for home, taking with them two hundred and fifty prisoners, belonging to the noblest families in Corcyra, whom they kept in safe custody, but treated with great consideration, hoping by means of them at some future time to recover their influence in the island. II It was not long before the effects of this impolitic breach with Corinth were sensibly felt by Athens. In the course of the following summer, Potidaea, a Corinthian colony, situated on the borders of Macedon, and included in the Athenian alliance, openly raised the standard of revolt, encouraged by promises from Sparta, and by the presence of a strong body of hoplites, sent for its support from Corinth. Potidaea was presently closely invested by an Athenian army and fleet, and the Corinthians pretended to make this a fresh ground of complaint, though they had themselves incited the city to throw off its allegiance to Athens.