Why were Ancient Sparta and Ancient Athens at war?
The underlying cause of the war was Sparta’s fear of the growth of the power of Athens. This is Thucydides’ own final judgment. The whole history of the rise and power of Athens in the 50 years preceding justifies this view, though the immediate occasion of the war concerned Corinth, Sparta’s chief naval ally. Since the peace of 445 B.C. Pericles had consolidated Athenian resources, made Athens’ navy incomparable, concluded in 433 B.C. a defensive alliance with the strong naval power Corcyra (Corinth’s most bitter enemy), and renewed alliances with Rhegium and Leontini in the west. The very food supply of the Peloponnese from Sicily was endangered. In the Aegean Athens could always enforce a monopoly of seaborne trade. To this extent the Peloponnesian War was a trade war and on this ground chiefly Corinth appealed to Sparta to take up arms. The appeal was backed by Megara, nearly ruined by Pericles’ economic boycott, and by Aegina a reluctant member of the Athenian Empire. But if Spart
