Thirty Years' Peace

In 446 or 445 BC, Athens and Sparta signed a treaty intended to last thirty years, ending a period of intermittent fighting historians call the First Peloponnesian War. Athens had tried to extend its power onto the Greek mainland, but a series of setbacks, including the loss of Boeotia and a revolt on Euboea, forced it to negotiate. The Athenian leader Pericles and the Spartan king Pleistoanax were the key figures on each side. Under the terms, Athens gave up most of its mainland possessions, while Sparta accepted Athenian control of its naval empire. The Greek world was effectively divided into two blocs, the Athenian empire at sea and the Spartan-led Peloponnesian League on land. Neither side was to interfere with the other's allies, and disputes were to be settled by arbitration. The peace allowed Athens to focus on its empire and on the building program of Pericles, including the Parthenon. It lasted about fourteen years, not thirty. Rising tensions over Corinth, Corcyra and Potidaea led to the outbreak of the Peloponnesian War in 431 BC.