Delian League
The Peloponnesian Wars were the protracted armed conflicts, waged on sea and land, of the last half of the 5th century BC between the Delian League controlled by Athens and the Peloponnesian League dominated by Sparta over control of the other Greek city-states. The Delian League is often called "the Athenian Empire" by scholars. The Peloponnesian League believed it was defending itself against Athenian aggrandizement.