Macedonian Empire

After the disputes that led to the weakening and dismantling of the two leading Greek city-states, a new regional power emerged; Macedonia, under the leadership of King Philip II, who had a strong enough military base to organize campaigns against Persia.  
At the battle of Chaeronia in 338 B.C., King Philip II established his dominance by defeating the united front of Athens and Thebes, and eventually forming a confederation of all the Greek city-states to stand against the Persian enemy.