The Persian Wars set the conditions for the Peloponnesian War because Sparta was concerned about the power and wealth Athens gained following the Persian Wars. Despite the fact that the Greeks combined, under the leadership of Sparta and Athens, defeated the Persians, they were not able to maintain their unity. Athens grew from just another city-state into a major trading and maritime power, that dominated the trade routes in the eastern Mediterranean and came out as a great Empire, breaking the balance of power. Traditionally, Sparta was the greatest military power in Greece. The rise of Athens meant that there were two great powers in old Greece and they became divided into a battlefield between these two city-states.
