Pericles, concerned over the draining effect of years of war on Athenian manpower, looks for peace with the support of the Assembly. Athenian diplomat, Callias, goes to Sparta and after much bargaining arranges a peace treaty with Sparta and her Peloponnesian allies, thus extending the 5 years truce of 452 BC for another 30 years. According to this treaty, Megara is to be returned to the Peloponnesian League, Troezen and Achaea become independent, Aegina is to become a tributary to Athens but autonomous, and disputes are to be settled by arbitration. Each party agrees to respect the alliances of the other.
The Temple of Poseidon is completed south of Athens at Cape Sunion.