Battle of Coronea (447 BC)

In 457 BC the Athenians had taken control of Boeotia at the Battle of Oenophyta, and spent the next ten years attempting to consolidate the League's power. In 454 BC Athens lost a fleet attempting to aid an Egyptian revolt against Persia; fearing revolts by the other members of the Delian League, Athens moved the treasury to their city from Delos in 453 BC, and signed the Peace of Callias with Persia around 450 BC.

The Delian League was essentially an Athenian empire, and while Athens was usually successful at holding their possessions in the Aegean Sea, they were less successful on land. By 447 BC some of the men exiled from Boeotia after the Athenian victory there in 457 had returned home and began to take back some of the Boeotian towns. The Athenians under Tolmides, with 1000 hoplites plus other troops from their allies, marched into Boeotia to take back the recaptured towns. They captured Chaeronea, but were attacked and defeated by the Boeotians at Coronea. The Athenians were forced to give up control of Boeotia, and the defeat led to revolts on Euboea and in Megara, which in turn led to further conflict with Sparta, contributing to the Peloponnesian War.