Aegina is an Island south of Salamis
, that for many years constituted the most important commercial power in Greece
, rivalled only by Corinth
. Aegina was a supporter of Sparta
and a part of the Peloponesian League
As Athens grew in strength and became an important marine power in the beginning of the 5th century BCE, Aegina initiated a war against it over the control of the island of Salamis, the war continued for 3 decades with the eventual victory of the Athenians. Aegina was forced to enter the Delian League.
In the compromise settelment between Athens and Sparta afer the First Peloponesian War, Sparta gave up all claims to Aegina and the Island became a full member of the Athenian Arche (aka the Athenian Empire), in the condition that Athens would not change the internal government of the island from aristocratic to democratic.
During the Second Peloponesian War Aegina rebelled successfully against Athens and joined the Spartan side.