Thirty Years' Peace

The Thirty Years' Peace was a treaty, signed between the ancient Greek city-states Athens and Sparta, in the year 446/445 BC. The treaty brought an end to the conflict commonly known as the First Peloponnesian War, which had been raging since c.460 BC.

The purpose of the treaty was to prevent another outbreak of war. Ultimately, the peace treaty failed in achieving its goal. Athens was forced to give up all of her possessions in the Peloponnese which included the Megarian ports of Nisaea and Pegae with Troezen and Achaea in Argolis, however the Spartans agreed to allow the Athenians to keep Naupactus. This also ruled out armed conflict between Sparta and Athens if at least one of the two wanted arbitration. Neutral poleis could join either side (i.e. Sparta or Athens and this implies that there was a formalized list of allies for each side. Athens and Sparta would keep all other territories pending arbitration. It also recognized both Leagues as legitimate, a boost for Athens and its newly formed empire in the Aegean.

The Thirty Years' Peace, however, only lasted 13 years. It ended when the Spartans had declared war on the Athenians. During the peace the Athenians took steps in undermining the truce. Athens participated in the dispute over Epidamus and Corcyra in 435 BC, which angered the Corinthians, who was an ally of Sparta. Athenian trade sanctions against the Spartan ally Megara due to its participation in the Corinthian/Corcyran dispute. In the year 432, Athens attacked Potidaea, which was a listed ally but a Corinthian colony. These disputes prompted the Spartans to declare that the Athenians had violated the treaty, thus declaring war. At this point the Thirty Years' Peace was void and the second Peloponnesian War (commonly known as the Peloponnesian War) began.