Answer: The city-states had allies near the Mediterranean Sea. The city-states were surrounded by water. How did conquering the Greek city-states achieve Philip II's goal for Macedonia? He wanted to spread Macedonia's religion and, In 368 BCE Philip II and Alexander III defeated the combined forces of Athens and Thebes at the Battle of Chaeronea and afterwards formed the Pan-Hellenic Congress with himself as its head. He had effectively conquered the Greek city-states and brought them under Macedonian control.