Athens was at first the leader of the Delian League; she soon became its ruler.
Many of the allied cities offered to send, as their contribution to the league, money instead of ships. To this Athens agreed gladly, and with the money she added ship after ship to her own fleet. So the navy of Athens continued to grow while that of the other states dwindled until they possessed only a few vessels.
The treasury of the league, which had been kept in the small but sacred island of Delos, was moved to Athens with the consent of the allies.
But after a time the other cities grew discontented. They complained that the money they sent to the league was not spent on ships alone. Some of it, at least, was used to build beautiful temples for the city of Athens.
So dissatisfied were they that they declared that they would leave the league. But they soon found that it would be difficult to carry out their threat, for Athens was too anxious to receive their contributions of money to let them go.
When the people who lived on the island of Samos revolted, Pericles went with an army to besiege their capital town, and after nine months the Samians were forced to surrender. The walls of the city were pulled down, the ships belonging to the island were seized, and the inhabitants were forced to pay a heavy fine.
On his return to Athens, Pericles was welcomed by his own party, but Elpinice, the sister of Cimon, was indignant that the citizens should rejoice at a victory gained over their own countrymen.
One day, soon after his triumphant return, Elpinice waylaid Pericles as he was walking along the streets, and said to him, "These are brave deeds, Pericles, that you have done, and such as deserve our chaplets, who have lost us many a worthy citizen, not in a war with Phoenicians or Medes, like my brother Cimon, but for the overthrow of an allied and kindred city."
Elpinice hoped to make Pericles ashamed that he had fought with people of his own race.
And now for two years, from 447 b.c. to 445 b.c. , loss after loss befell Athens. While she was struggling with her other enemies, the king of Sparta marched into Attica with an army. Athens herself was in danger.
But before the army reached the city, it was ordered to halt, and soon after it withdrew from Attica.
No one knew what had made the Spartans spare Athens, but it was said that Pericles had paid their king a large sum of money on condition that he took his army back to his own country.
In 445 b.c. Athens signed a Thirty Years' Truce with Sparta, and at the same time peace was made with Persia.
Pericles was now able to devote himself to the work which was his greatest pleasure. He spent fourteen years in making Athens so beautiful that it became the wonder city of the world.