Remember back at the beginning, when Athens and Sparta both wanted to keep the Persians out of Greece? Even though they won, the victory didn’t exactly make them great pals. After the two most powerful city-states in Greece defeated their common enemy, the rivalry between them heated up again. This led to a long string of battles known as the Peloponnesian War.
How did it begin? The leaders of Athens wanted more power over other city-states, so they turned the Delian League into their own Athenian Empire. Athens became very wealthy from the tributes it received. Pericles used a lot of the money to strengthen the city’s defense walls, known as the Long Walls. They protected the route between Athens and its port of Piraeus, about seven miles away. Pericles also built up the Athenian fleet, which was already the biggest navy around. Athens used its powerful navy to pressure more city-states to accept its rule.