The First Peloponnesian War, fought between Sparta as the leaders of the Peloponnesian League and Sparta's other allies, most notably Thebes, and the Delian League led by Athens with support from Argos, consists of a series of conflicts and minor wars, such as the Second Sacred War.

There are several causes for the war including the building of the Athenian Long Walls, Megara's defection and the envy felt by Sparta at the growth of the Athenian Empire.The war begins in 460 BCE.

At first the Athenians have the better of the fighting, winning the naval engagements using their superior fleet.

They also have the better of the fighting on land, until 457 BCE when the Spartans and their allies defeat the Athenian army at Tanagra.

The Athenians, however, counterattack and score a crushing victory over the Boeotians at the Battle of Oenophyta and follow this victory by conquering all of Boeotia except for Thebes.Athens further consolidates her position by making Aegina a member of the Delian League and by ravaging the Peloponnese.

The Athenians are defeated in 454 BCE by the Persians in Egypt which causes them to enter into a five years' truce with Sparta.

However, the war flares up again in 448 BCE with the start of the Second Sacred War.

In 446 BC, the Boeotians revolt, defeating the Athenians at Coronea and regaining their independence.The First Peloponnesian War ends in an arrangement between Sparta and Athens, which is ratified by the Thirty Years' Peace (winter of 446–445 BCE).

According to the provisions of this peace treaty, both sides maintain the main parts of their empires.

Athens continues its domination of the sea while Sparta dominates the land.

Megara returns to the Peloponnesian League and Aegina becomes a tribute-paying but autonomous member of the Delian League.

The war between the two leagues will restart in 431 BCE and in 404 BCE, Athens will be occupied by Sparta.