The Delian League, also 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 confederation's affairs were handled by a synod which met, from time to time, in the temple of Apollo located 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 larger Sparta-led opposition. At the start of the war only the islands of 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 in 404 B.C. when the Peloponnesian war ended.
Athens tried to regain her power and influence with a confederacy of Aegean Sea city-states primarily for self-defense against the growth of Sparta and the Persian Empire. This attempt to rebuild her empire began in 378 B.C. In 357 B.C. what is known as the Social War broke out. It pitted the Athenians against former League members from the islands of Chios, Rhodes and Kos assisted by the independent city of Byzantion (also known as Byzantium, later renamed Constantinople). When the conflict ended in 355 so too did attempts at rebuilding the empire.
The Bible records that the apostle Paul visited Athens in 49 A.D. and preached the gospel within the city.
15. Now those who were conducting Paul brought him to Athens; and after receiving Paul's command to Silas and Timothy to come to him as quickly as possible, they departed. 16. But while Paul was waiting for them in Athens, he saw that the city was wholly given to idolatry, and his spirit was sorely moved within him.
22. Then Paul stood in the center of Mars' hill and said, "Men, Athenians, I perceive that in all things you are very reverent to deities; 23. For as I was passing through and observing the objects of your veneration, I also found an altar on which was inscribed, 'To an unknown God.' So then, He Whom you worship in ignorance is the one that I proclaim to you. (Acts 17:15 - 16, 22 - 23, HBFV)