The decades after the end of the Peloponnesian War were turbulent ones. The chief states — Sparta, Athens, and Thebes — each tried to create a political system in which it would dominate. When Athens surrendered to Sparta in 404 B.C.E., the Spartans used their victory to build an empire. Their decision brought them into conflict with Persia, which now demanded the return of Ionia to its control, as Sparta had promised earlier. From 400 to 386 B.C.E. the Spartans fought the Persians for Ionia, a conflict that eventually engulfed Greece itself. After years of stalemate the Spartans made peace with Persia and their own Greek enemies. The result was a treaty, the King’s Peace of 386 B.C.E. in which the Greeks and Persians pledged themselves to live in harmony. This agreement cost Sparta its empire but not its position of dominance in Greece.

The Spartans were not long content with this situation, however, and decided to punish cities that had opposed Sparta during the war. They used naked force against old enemies even though they had formally agreed to peace. In 378 B.C.E. the Spartans launched an unprovoked attack on Athens. Together the Thebans and the Athenians created what was called the Second Athenian Confederacy, a federation of states to guarantee the terms of the peace treaty. The two fought Sparta until 371 B.C.E., when due to growing fear of Theban might, Athens made a separate peace with Sparta. Left alone, Thebes defended itself until later that year, when the brilliant Theban general Epaminondas (ih-pah-muh-NAHN-duhs) (ca. 418–362 B.C.E.) routed the Spartan army on the small plain of Leuctra and in a series of invasions eliminated Sparta as a major power.

The defeat of the once-invincible Spartans stunned the Greeks, who wondered how Thebes would use its victory. Epaminondas, also a gifted statesman, immediately grappled with the problem of how to translate military success into political reality. He concluded alliances with many Peloponnesian states but made no effort to dominate them, instead creating a federal league of cities in which people could marshal their resources, both human and material, to defend themselves from outside interference. Although he made Thebes the leader of this federation of cities, other city-states and leagues were bound to Thebes only by voluntary alliances. His premature death at the Battle of Mantinea in 362 B.C.E. put an end to his efforts, however.