Cleomenes defeats the armies of the Achaean confederacy at Mount Lycaeum and Ladoceia, near Megalopolis, in 227BCE.
He bribes the ephors, the main governmental body, later in the year to allow him to continue his campaign against the Achaeans.
Having succeeded with his bribe, Cleomenes advances into the territory of Megalopolis and captures the village of Leuctra.
In response, an Achaean army arrives to relieve the city and inflicts a minor defeat on the Spartan army based nearest the city walls.
Cleomenes is therefore obliged to retreat with his troops across a series of ravines.
Aratus orders the Achaeans not to pursue the Spartans across the ravine, but Lydiadas of Megalopolis disobeys the order and charges with the cavalry in pursuit of the Spartans.
Cleomenes, taking advantage of the difficult terrain and the scattered cavalry, sends his Cretan and Tarentine soldiers against Lydiadas.
They rout the cavalry, and Lydiadas is among the dead.
The Spartans, encouraged by these events, charge against the main Achaean forces and defeat the entire army.
The Achaeans are so outraged and demoralized by Aratus' failure to support Lydiadas that they make no further attacks in this year.
Cleomenes, now confident of the strength of his position, begins plotting against the ephors.
He first recruits his stepfather, persuading him of the need to do away with the ephors.
Cleomenes contends they could then make the ephors' property common to all citizens and work toward the achievement of Spartan supremacy in Greece.
Having won over his stepfather, Cleomenes starts preparing his revolution.
Employing the men he considers most likely to oppose him (probably in an attempt to get them killed), he captures Heraea and Asea.
He also brings in food for the citizens of Orchomenus—which the Achaeans are besieging—before camping outside Mantinea.
This campaign exhausts his opponents, who ask to remain in Arcadia so they can rest.
Cleomenes then advances upon Sparta with his mercenaries and sends some loyal followers to slay the ephors.
All of the five ephors are killed, with the exception of Agylaeus, who manages to escape and seeks sanctuary in a temple.
With the ephors vanquished, Cleomenes initiates his reforms.
Combining a narrow Spartan nationalism with a visionary idealism, he begins to break the power of the oligarchy within the aristocracy, abolish the debts owed by poor farmers to rich landlords, and redistribute the land.
He also reintroduces the common meals and restores the simplicity of life and the education for character that had been traditional in Sparta.
The revolution spreads; everywhere there is demand for “division of land and cancellation of debts.” First, he hands over his land to the state; he is soon followed by his stepfather and his friends, and then by the rest of the citizens.
He divides up all of the Spartan land, awarding an equal lot to each citizen.
He increases the citizen population by granting citizenship to some perioeci, who constitute the Spartan middle class, but do not at this time have Spartan citizenship.
Expanding the citizen population means that Cleomenes can build a larger army; he trains four thousand hoplites and restores the old Spartan social and military discipline.
He also strengthens his army by introducing the Macedonian sarissa (pike).
Ptolemy III of Egypt offers continued assistance to Cleomenes on the condition that the Spartan king offer his mother and children as hostages.
Cleomenes hesitates but his mother, after learning of Ptolemy's offer, goes voluntarily to Egypt.
