As you learned earlier, Sparta and Athens worked together to win the Persian Wars. The Spartans fought most of the battles on land, and the Athenians fought at sea. After the war, the powerful Athenian fleet continued to protect Greece from the Persian navy. As a result, Athens had a great influence over much of Greece.

Athenian Power

After the Persian Wars ended in 480 BC, many city-states formed an alliance, or an agreement to work together. They wanted to punish the Persians for attacking Greece. They also agreed to help defend each other and to protect trade in the Aegean Sea. To pay for this defense, each city-state gave money to the alliance. Because the money was kept on the island of Delos, historians call the alliance the Delian League.

With its navy protecting the islands, Athens was the strongest member of the league. As a result, the Athenians began to treat other league members as their subjects. They refused to let members quit the league and forced more cities to join it. The Athenians even used the league's money to pay for buildings in Athens. Without even fighting, the Athenians made the Delian League an Athenian empire.

The Peloponnesian War

The Delian League was not the only alliance in Greece. After the Persian Wars, many cities in southern Greece, including Sparta, banded together as well. This alliance was called the Peloponnesian League after the peninsula on which the cities were located. The growth of Athenian power worried many cities in the Peloponnesian League. Finally, to stop Athens's growth, Sparta declared war.

This declaration of war began the Peloponnesian War, a war between Athens and Sparta that threatened to tear all of Greece apart. In 431 BC the Spartan army marched north to Athens. They surrounded the city, waiting for the Athenians to come out and fight. But the Athenians stayed in the city, hoping that the Spartans would leave. Instead, the Spartans began to burn the crops in the fields around Athens. They hoped that Athens would run out of food and be forced to surrender.

The Spartans were in for a surprise. The Athenian navy escorted merchant ships to Athens, bringing plenty of food to the city. The navy also attacked Sparta's allies, forcing the Spartans to send troops to defend other Greek cities. At the same time, though, disease swept through Athens, killing thousands. For 10 years neither side could gain an advantage over the other. Eventually, they agreed to a truce. Athens kept its empire, and the Spartans went home.

A few years later, in 415 BC, Athens tried again to expand its empire. It sent its army and navy to conquer the island of Sicily. This effort backfired. The entire Athenian army was defeated by Sicilian allies of Sparta and taken prisoner. Even worse, these Sicilians also destroyed most of the Athenian navy.

Taking advantage of Athens's weakness, Sparta attacked Athens, and the war started up once more. Although the Athenians fought bravely, the Spartans won. They cut off the supply of food to Athens completely. In 404 BC, the people of Athens, starving and surrounded, surrendered. The Peloponnesian War was over, and Sparta was in control.

Fighting Among the City-States

With the defeat of Athens, Sparta became the most powerful city-state in Greece. For about 30 years, the Spartans controlled nearly all of Greece, until other city-states started to resent them. This resentment led to a period of war. Control of Greece shifted from city-state to city-state. The fighting went on for many years, which weakened Greece and left it open to attack from outside.