The Delian League was an association of 5th-century B.C. Greek city-states under the leadership of Athens, whose purpose was to continue fighting the Persian Empire after the Greek victory in the Battle of Plataea at the end of the Greco–Persian Wars.
Founded in 478 B.C., the League's name derives from its official meeting place, the island of Delos. Shortly after its inception Athens began to exploit the League's navy for its own benefit. By 454 B.C. the Delian League could be fairly characterized as the Athenian Empire.
Athens use of the League would frequently lead to conflict between them and less powerful League members. By 431 B.C. Athens' heavy-handed control of the Delian League would prompt the outbreak of the Peloponnesian War.
At the start of the Peloponnesian War (where the Athenian empire fought the Peloponnesian League led by Sparta), only Chios and Lesbos were left to contribute ships to the Delian league, and these states were by now far too weak to revolt without support.
Athens' empire was not very stable and dissolved upon the conclusion of the Peloponnesian war in 404 B.C.