Confederacy of ancient Greek states led by Athens and based on the island of Delos .
Founded in 478 BC to combat Persia, its members included Aegean states and islands; Athens supplied commanders and assessed tributes of ships or money. It achieved a major victory in 467–466 when its fleet drove out Persian garrisons on the southern Anatolian coast. After 454 its leaders moved the treasury to Athens for safekeeping, used it to rebuild the city's temples, and treated the league as the Athenian empire. Most league members sided with Athens in the Peloponnesian War , which diverted the league from its Persian campaign. After defeating Athens in battle in 405, Sparta disbanded the league in 404. Fear of Sparta helped revive the league in the early 4th century, but it weakened as Sparta declined and was crushed by Philip II at the Battle of Chaeronea (338).