18 Outbreak of the Peloponnesian War

Although Athens and Corinth clashed over Corcyra in the autumn of 433 B.C., neither side had declared that the Thirty Years’ Peace had been violated. The Spartans were not yet involved, and the crisis need not have escalated into a general war. Pericles, however, erred in securing passage of the Megarian Decree (an embargo on Megara) as a warning to Corinth. Corinth responded in the spring of 432. B.C. by backing the rebellion of Potidaea, the Athenian ally in the Chalcidice. Potidaea, a former Corinthian colony, appealed for Spartan assistance. After hearing the appeals of their allies and the explanations of the Athenians, the Spartan assembly voted for war in the summer of 432 B.C. Thucydides believed that the vote was inevitable, given the Spartans’ fear of Athenian power. If so, neither Sparta nor Athens was prepared to go to war in 432 B.C. Furthermore, the Spartans offered to desist from war if the Megarian Decree was rescinded. The Athenians responded with offers of arbitration. The Spartans refused to acknowledge parity with Athens, and the Athenians refused to accept a subordinate role. Political perceptions more than tangible interests drove the two states to declare war.