Answer:
The Greek city-states were battling among them, resulted became weak.
Step-by-step explanation:
Philip second was the king of the ancient Greek kingdom of Macedonia, located in the northern peninsula of Greece. He took advantage of the weakness of the other city-states like Athens, Sparta, Thebes, etc because their continuous fighting among them had made them weak. Other vital reasons for his success were the reformation of the Ancient Macedonian Army, changes to his cavalry and siege equipments, the establishment of the Macedonian Phalanx, which appeared to be crucial in preserving victories on the battlefield.