Delian League

Delian League, federation of city-states of ancient Greece, whose main purpose at the time was to prepare against a possible renewal of aggression by Persia. The league, sometimes called Confederation of Delos, was founded in 477 bc after the failure of a Persian attempt to invade Greece. Because it appeared probable that Persian aggression might come by sea rather than by land, Athens, as the greatest sea power in Greece, became the leading member of the league. The confederation had its headquarters on the island of Delos, and each of the member states, which at one time numbered more than 200, made a contribution in manpower and equipment in proportion to its resources. As time passed, fewer of the allies in the league contributed men and ships, most of them substituting money payments, which became in effect tribute to Athens. As this trend continued, the program of the league gradually changed from one of defense against Persia to that of strengthening Athens. When several members were restrained by force from seceding, the alliance of sovereign states was transformed into what modern scholars call the Athenian Empire.

By 449 bc, when the Peace of Callias ended the war against Persia, all but three of the allies were paying their contribution in money. Five years earlier the treasury had been moved from the temple of Apollo at Delos to Athens, and the following year several city-states on the Greek mainland, having nothing to fear from Persia but much to gain by winning Athenian support, joined the league. From this period until the conclusive defeat of Athens by Sparta in the Peloponnesian War in 404 bc, members of the Delian League were vassals of Athens. After the conquest of the latter, the league disintegrated, but it was reconstituted in 377 bc by those states that feared Spartan power. Following the conclusion of peace with Sparta (371) the league again became a group of Athenian subject states, but Athens was no longer able to enforce its authority, and the membership of the league constantly fluctuated. After King Philip II of Macedonia defeated the Athenians at Chaeronea in 338 bc, the league ceased to exist.

Modern scholars have studied the organization of the Delian League and the changing relationships of the members with great interest, because this organization is the first example in history of a federal alliance of sovereign states maintained over a long period, and in one of its phases is the first example of what has become known as imperialism.