What leads to war and the end of Athens' imperialism?

The imperialistic quest of the Athenians is now directed at other Greek city-states. This leads to war, eventually. The Athenians manage to hold together their system of democracy, until it is destroyed by the Macedonians in 322 B.C. At the end of the war in 230 B.C., Athens establishes a democratic republic, bringing their imperialism to an end.