From 229 BC to 222 BC, Cleomenes waged war against the Achaean League under Aratus of Sicyon. He defeated them in three battles before the Achaeans, receiving military aid from Antigonus III Doson of Macedon, defeated him at the Battle of Sellasia in 222 BC.
Following his defeat, he fled from Sparta and went to the court of his ally, Ptolemy III of Egypt hoping that he would help him regain his throne. However, when Ptolemy died, his son and successor, Ptolemy IV neglected Cleomenes and eventually put him under house arrest. Together with his friends, he escaped his house arrest and tried to incite a revolt. When he received no support from the population of Alexandria, he committed suicide in 219 BC.
Cleomenes was born in Sparta to King Leonidas II and his wife Cratesicleia and was part of the Agiad dynasty. The exact year of Cleomenes' birth is unknown but historian Peter Green puts it between 265 BC and 260 BC. As part of his agoge and in keeping with the native pederastic tradition he was the aites (hearer) of Xenares. Later he would be the eispnelos (inspirer) of Panteus, who died with him a heroic death.
In around 242 BC, Leonidas was exiled from Sparta and forced to seek refuge in the temple of Athena after opposing the reforms of the Eurypontid King, Agis IV. Cleomenes' brother-in-law, Cleombrotus who was a supporter of Agis became king. Meanwhile, Agis IV having started his reforms went on a campaigning near the Isthmus of Corinth which presented Leonidas a to regain his throne. He quickly desposed of Cleombrotus and when Agis returned to Sparta, he had him captured and executed.
Following the execution of Agis, Cleomenes - who was around eighteen at the time - was made by his father to marry Agis' widow, Agiatis, who was a wealthy heiress. According to legend, Cleomenes was hunting when his father sent him a message telling him to return immediately to Sparta. When he returned to the city, he saw that it was being decorated for a wedding and when he asked his father who was getting married, his father replied that Cleomenes was. It was reported that Cleomenes was doubtful about the marriage because his father had Agiatis' husband executed. The marriage worked out and Agiatis told Cleomenes about Agis and his plan.
|"Upon this, Cleomenes wrote to him, in a familiar way, desiring to know, "Whether he marched the night before." Aratus answered, "That, understanding his design to fortify Belbina, the intent of his last motion was to prevent that measure." Cleomenes humorously replied, "I am satisfied with the account of your march; but should be glad to know where those torches and ladders were marching."|
|The conversation between Cleomenes and Aratus according to Plutarch.|
On the death of his father, Cleomenes ascended the throne of Sparta in 235 BC. Cleomenes had been inspired by Agis and began reforms. Meanwhile, the Achaean League under the command of Aratus of Sicyon was trying to united all of the Peloponnese. Upon hearing of Leonidas' death, Aratus began attacking the cities of Arcadia which bordered Achaea. Plutarch says that Aratus made these moves to see how Sparta stood inclined.
In 229 BC, the cities of Tegea, Mantinea, Caphyae and Orchomenus - who where allied with the Aetolian League - come over to Sparta. Historians Polybius and Sir William Smith claim that Cleomnes seized these cities by treachery however the translator of Plutarch on Sparta, Richard Talbert, claims he did so at their own request. Later that year, the ephors sent Cleomenes to seize Athenaeum, a border fort on the Spartan border with Megalopolis which was being disputed by both cities; Cleomenes seized the fort and fortified it. Meanwhile, the Achaean League summoned a meeting of its assembly and declared war against Sparta. In retaliation for fortifing the fort, Aratus made a night attack on Tegea and Orchomenus but when his supporters on the inside failed to help, he retreated hoping to remain unnoticed.
Cleomenes discovered the attempted night attack, and sent a message to Aratus asking the purpose of the expedition. Aratus replied that he had come to stop Cleomenes fortifing Athenaeum. Cleomenes responded to this by saying: "if it's all the same to you, write and tell me why you brought along those torches and ladders."
Cleomenes advanced into Arcadia before being called back by the ephors. When Aratus captured Caphyae, the ephors sent him out again. He ravaged the territory of Argos with an army of 5,000 men before being confronted by the new strategos of the Achaean League, Aristomachos of Argos consisting of 20,000 infantry and 1,000 cavalry at Pallantium. Aratus, who accompanied Aristomachos as an adviser, advised him to retreat. Smith agrees with Aratus' assessment that 20,000 Achaeans were no match for 5,000 Spartans.
This success greatly encouraged Cleomenes and when he heard that Aratus was attacking Sparta's ally, Elis, he set off to confront them. The Spartan army fell upon the Achaean army near Mount Lycaeum and routed it. Aratus took advantage of a rumour saying that he had been killed in the battle and seized Mantinea. His blow took the war spirit out of the Spartans and they began to oppose Cleomenes' war effort.
Meanwhile, the Eurypontid King of Sparta, Eudamidas III, who was the son of Agis IV and Agiatis died. Cleomenes' recalled his uncle, who had fled after Agis' execution to Messene to assume the throne. However, as soon as he returned to Sparta he was assassinated. Cleomenes' part in the assassination is unknown with Polybius claiming that he ordered it, but Plutarch disagrees.
Having bribed the ephors to allow him to continue campaigning, Cleomenes advanced into the territory of Megalopolis and started to besiege the village of Leuctra. As Cleomenes was besieging the village, an Achaean army under the command of Aratus attacked the Spartans. In the initial attack, the Spartans were repelled. However, Lydiadas of Megalopolis, the cavalry commander, disobeyed Aratus' order not to pursue the Spartans. As the cavalry scattered as they were trying to cross some difficult terrain, Cleomenes' skirmishers managed to defeat them. Encouraged by this counter-attack, the Spartans charged the main body of the Achaean army and routed them.
Confident of his strong position, Cleomenes began plotting against the ephors. After gaining the support of his stepfather, he embarked took his opponents with him on a whirlwind military expedition and when they requested to stay in Arcadia due to exhaustion he returned to Sparta to carry out his plan. When he reached the city, he sent some of his loyal followers to kill the ephors. All five of the ephors killed except for Agylaeus, whho manahed to escape and seek sanctuary in a temple.
Having removed the ephors, Cleomenes began his reforms. He first handed over all his land to the state; he was soon followed by his stepfather and his friends and the rest of the citizens. He divided up all the land and gave an equal lot to every citizen. To increase the declining Spartan citizen body, he made some perioeci, citizens. He trained 4,000 hoplites and restored the ancient Spartan military and social discipline as well as equipping his army with the Macedonian sarissa (pike) which greatly strengthened the army.