The Delian League, as known as the Confederacy of Delos, was an association of Greek city-states under the leadership of Athens. The Athenians assumed a lead role in the confederation due to their display of naval power against the Persians. Founded in 478 B.C., the League's name derives from its official meeting place, the island of Delos. The affairs of the confederation were managed by a synod which met periodically in the temple of Apollo and Artemis on the island.
The initial goal of the League was to continue fighting the Persian Empire after the Greek victory in the Battle of Plataea at the end of the Greco–Persian Wars.
The League occupies a special place in history even though its existence was not very long. It is the first known serious attempt of a large number of self-governing states to unite for a common purpose. Each of the states had their own military, financial and judicial systems which led to a certain amount of autonomy.
Shortly after the League's inception Athens began to exploit it 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. their heavy-handed control led to the outbreak of the Peloponnesian War, which pitted the Athenians and her allies against a Sparta-led opposition. At the start of the war, however, only Chios and Lesbos were left to contribute ships to the Delian league, and these states were 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.