of Pericles the Athenians decided on an alliance with Corcyra, principally because of the advantage it presented for ships sailing to Italy or Sicily, on which the eyes of the Athenians had long been fixed, as offering great opportunities for trade and settlements for their citizens. Accordingly, when the war between Corinth and Corcyra was renewed in B.C. 433, the Corinthians were prevented from taking advantage of a naval victory off the Sybota Islands by an Athenian squadron.
The Corinthians, therefore, were anxious to find some means of retaliating upon Athens, and this was afforded them in the following year (B.C. 432), by the revolt of Potidaea, which was a colony of their own, from the Athenian alliance. The revolt had been originally instigated by the king of Macedonia, who wished to get control over the Chalcidian peninsula. The people of Potidaea applied to Corinth for help, which was readily given, and still more effective aid promised. But the Athenians were too quick for them, and the town was soon completely blockaded by a strong Athenian force of men and ships, though it managed to hold out till the winter of B.C. 430.
The Corinthians now sent envoys to Sparta denouncing the ambition and tyranny of Athens. The Spartans summoned a conference of their allies, and after long deliberation war with Athens was resolved upon. It was not begun at once. Embassies went backwards and forwards, and various demands were made, partly with a view of putting
Athens in the wrong, partly in order to gain time
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