Delian League, confederacy of ancient Greek states under the leadership ofAthens, with headquarters atDelos, founded in 478bce during theGreco-Persian wars. The original organization of the league, as sketched byThucydides, indicates that all Greeks were invited to join to protect themselves fromAchaemenianPersia. In fact, Athens was interested in further supporting theIonians inAnatolia and exactingretribution from the Persians, whereasSparta was reluctant to commit itself heavily overseas. The Athenians were to supply the commanders in chief and to decide which states were to provide ships or money; money was to be received and controlled by 10 Athenian treasurers (hellēnotamiai). Representatives of all member states, each with equal vote, met annually at Delos, where the league’s treasury was kept in the temple ofApollo. The original membership probably included most of theAegean islands, exceptAegina,Melos, andThera, most of the cities ofChalcidice, the shores of theHellespont andBosporus, some ofAeolia, most ofIonia, and a few easternDorian and non-GreekCarian cities.

Action taken against Persia in the first 10 years was scattered: the Persian garrison was expelled from Eion, Thrace; an Athenian settlement (cleruchy) sent to that district was destroyed by the natives, but one sent to the island of Scyros was successful; the cities of the Thracian coast were won over; and Doriscus, unsuccessfully attacked, remained the only Persian garrison left in Europe. A major victory was achievedc. 467–466 when the Athenian commander,Cimon, heading a largeconfederate fleet along the southern coast of Anatolia, drove out Persian garrisons and brought the coastal cities into the league. He then defeated the Persian fleet on the Eurymedon atPamphylia, sacked their army camp, and routed their Cyprian reinforcements.

League policy entered a new phase as relations between Athens and Sparta broke down in 461. The Athenians committed themselves to war with thePeloponnesian League (460–446), at the same time launching a large-scale eastern offensive that attempted to secure control ofCyprus,Egypt, and the easternMediterranean. While the Athenians and allies were campaigning successfully against the Spartans, subjugating Aegina,Boeotia, and centralGreece, further expansion was checked when the leaguefleet was virtually destroyed in Egypt. Fearing the Persians would mount an offensive following such a naval defeat, the Athenians transferred the league treasury to Athens (454). Within the next five years, with the resolution of difficulties with Sparta (five-year truce, 451) and Persia (Peace of Callias,c. 449/448), the league became an acknowledged Athenianempire.

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ancient Greek civilization: The Delian League

Athenianimperialism had been evident as early asc. 472, when Carystus, inEuboea, was forced into the league, andNaxos, wishing to secede, was reduced and subjugated. AThasian revolt was crushed in 463, and during the 450s there were anti-Athenian movements inMiletus,Erythrae, andColophon. The allies’ independence was progressively undermined, as Athenians interfered in their internal politics (imposingdemocracies and garrisons) and in their legal jurisdictions. League council meetings finally ceased, and the Athenians proceeded to use the league reserves to rebuild the Athenian temples destroyed by the Persians. Athenian participation in thePeloponnesian War (431–404) placed further strains on the allies: increased tribute to finance the war and increased military support to replace Athenian losses were demanded. But despite revolts atMytilene (428–427) and Chalcidice (424) and widespread uprisings following Athenian defeat inSicily (413), Athens was still supported by the democratic parties in most of the cities. After defeating the Athenians at Aegospotomi (405), Spartaimposed peace terms that disbanded the league in 404.

Ineffectual Spartan management of the former empire after 404 aided the revival of Athenian influence. By 377 Athens, withCos, Mytilene, Methymna,Rhodes, andByzantium, formed the nucleus of a new naval league, whose objective was to preserve peace and prevent Spartan aggression. Membership had grown to at least 50 states at the time of the defeat of the Spartans by the Boeotians in 371, but with the elimination of the common fear of Sparta that had kept the allies together, the league declined. It was effectively crushed byPhilip II ofMacedon atChaeronea in 338.