Persia had been driven out of the Aegean Islands

The Persians were decisively defeated at sea by a primarily Athenian naval force at the Battle of Salamis, and on land in 479 at the Battle of Plataea. The alliance against Persia continued, initially led by the Spartan Pausanias but from 477 by Athens, and by 460 BC Persia had been driven out of the Aegean Islands. During this long campaign, the Delian league gradually transformed from a defensive alliance of Greek states into an Athenian empire, as Athens' growing naval power intimidated the other league states.