Because of the leading role played by Athens in repelling the Persians, she was able to group around her the many small cities of the Aegean islands, the Asia Minor coastline, the Euxine Sea, Thrace and Macedonia to form the Delian League (478/7 B.C.). The Delian League began as a military alliance of supposedly autonomous and equal city-states under Athenian leadership. However, during the mid-5^thcentury B.C. the ever-increasing frequency of Athenian interference in the internal affairs of the allied cities led to the gradual transformation of the League into an Athenian hegemony.

Some scholars distinguish three stages in the changing character of the League. In the first phase (478-461 B.C.) Cimon’s military successes contributed to the imposition of Athenian dominance over many areas of the League. Moreover, the transfer of the allied treasury from Delos to Athens (454 B.C.), the establishment of cleruchies (from 450 B.C.) and the imposition of Athenian currency, weights and measures on the allied cities (449 B.C.) constiute clear evidence of Athens’ hegemonic ambitions. During the second phase (461-431 B.C.) there was a breach between Athens and Sparta, which regarded this blatant Athenian expansionism with suspicion. The third phase (445-431 B.C.) coincides with the apex of Athenian power, and her tendency to protect her interests.

Athenian hegemony, combined with the gradual elimination of the fear of the Persian threat, alienated the members of the Delian League, some of whom subsequently left the alliance. In the long run, it created an atmosphere which contributed to the start of the Peloponnesian War.