Cleomenean War

A war fought from 229 to 222 BCE between Sparta under Cleomenes III and the Achaean League, eventually aided by Macedon. It ended with Macedonian victory and weakened Spartan power.

Cleomenes III: A Spartan king who ruled from 235 to 222 BCE and led Sparta during the Cleomenean War. His military reforms and campaigns made Sparta the war’s driving force.
Agis IV: A Spartan king who pursued land redistribution and civic reforms in the late third century BCE. His failed reform program preceded and influenced Cleomenes’ later reforms.
Spartan revolution: The constitutional and social transformation carried out at Sparta under Cleomenes III in the late third century BCE. Cleomenes used wartime power to abolish the ephorate and redistribute land.
Aetolian League: A federal alliance of Greek communities centered in Aetolia, influential in the Hellenistic period. It was a major Greek league outside the Achaean-Macedonian coalition that defeated Sparta.
Aratus of Sicyon: A Greek statesman and general who led the Achaean League for much of the third century BCE. He sought Macedonian support when Achaean forces could not contain Cleomenes.
Spartan Constitution: The political and social system traditionally attributed to the lawgiver Lycurgus and practiced at Sparta. Its institutions and inequalities formed the setting for Cleomenes’ changes.
Ephors: Five annually elected magistrates who supervised Sparta’s kings and civic affairs. Cleomenes’ abolition of the ephorate became a defining act of his revolution.
Macedonian–Achaean alliance: A military partnership between Macedon and the Achaean League formed during the Cleomenean War. It countered Sparta’s expansion and determined the conflict’s final balance.
Achaean League: A federal alliance of Greek cities in the Peloponnese, prominent in the third and second centuries BCE. The league was Sparta’s principal opponent throughout the conflict.
Social War (220–217 BC): A conflict led by Macedon against the Aetolian League and its allies from 220 to 217 BCE. It followed the Cleomenean War but involved a different coalition and principal adversaries.

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Philip V of MacedonBroader topic: Its outcome strengthened Macedon before Philip began ruling independently.