Cleomenes I

Cleomenes was an Agiad King of Sparta in the late 6th and early 5th centuries BC. During his reign, which started around 519 BC, he pursued an adventurous and at times unscrupulous foreign policy aimed at crushing Argos and extending Sparta's influence both inside and outside the Peloponnese. He was a brilliant tactician. It was during his reign that the Peloponnesian League came formally into existence. During his reign, he intervened twice successfully in Athenian affairs but kept Sparta out of the Ionian Revolt. He died in prison in mysterious circumstances, with the Spartan authorities claiming his death was suicide due to insanity.