2. The Persian Wars (492-479 BC): The Persians invaded Greece in retaliation for the Ionian Revolt. The Greeks were able to defeat the Persians at the Battle of Marathon (490 BC) and the Battle of Salamis (480 BC).
3. The Athenian Expansion (479-431 BC): After the Persian Wars, Athens became the leading city-state in Greece. Athens formed the Delian League, an alliance of Greek city-states, to protect themselves from the Persians. However, the Delian League soon became an Athenian empire, as Athens used its power to dominate its allies.
4. The Peloponnesian War (431-404 BC): The Peloponnesian War was a conflict between Athens and Sparta, the two most powerful city-states in Greece. The war lasted for 27 years and resulted in the defeat of Athens and the rise of Sparta.