During the Persian War, the Persians sent well-equipped armies to Greece. They attached the Athenians by sea, but the Athenians were prepared and defeated them.
The Athenians participated in a defensive league called the Delian League. Since they joined, the Athenians gained more power over the city-states. After a while, the Delian League became the Athenian Empire.
Soon the Athenians became hated and a war broke out between Sparta and Athen. The Spartans took