How a Spartan King Tried to Remake His City and Conquer the Peloponnese
In 229 BC, Cleomenes III launched a radical campaign to restore Spartan discipline and seize control of the Peloponnese. By reforming the social order and arming his troops with Macedonian pikes, he nearly succeeded—until his ambition forced his enemies to unite against him in a final, decisive clash.
Ascending the throne in 235 BC, Cleomenes III sought to dismantle the power of the ephors and restore traditional Spartan authority. His military expansion into Arcadia and his victory at Dyme in 226 BC pushed the Achaean League to the brink of collapse. To sustain his momentum, Cleomenes implemented sweeping reforms, including land redistribution and the expansion of the citizen body, while adopting the Macedonian sarissa to modernize his army.
The tide turned when Aratus of Sicyon, the Achaean leader, secured an alliance with Antigonus III Doson of Macedon. This partnership proved formidable, as Antigonus brought a massive force into the Peloponnese, eventually forcing Cleomenes to abandon his defensive lines at the Isthmus of Corinth. The conflict escalated into a total war, marked by the brutal destruction of Megalopolis in 223 BC and a desperate scramble for resources after Ptolemy III of Egypt withdrew his financial support.
The war culminated in 222 BC at the Battle of Sellasia. Cleomenes positioned his 20,000 troops on the hills of Evas and Olympus, but he was overwhelmed by Antigonus’s superior force of nearly 30,000 men. The defeat was catastrophic; only 200 of the 6,000 Spartan hoplites survived. Cleomenes fled to Egypt, where he eventually took his own life, marking the end of his attempt to restore Spartan hegemony.
The legacy of the Cleomenean War remains a subject of historical debate. While some ancient accounts, such as those by Polybius, emphasize the treachery involved in Cleomenes's territorial gains, others like N. G. L. Hammond suggest his occupation of Arcadian cities was requested by the locals. Regardless of the interpretation, the war fundamentally reshaped the power dynamics of Greece, cementing Macedonian influence and signaling the decline of independent Spartan power.
Source: Cleomenean War
