In 275 BC, after
campaigning in Italy and Sicily for seven years, King Pyrrhus of Epirus returned to Epirus. His treasury depleted by his western campaigns, he planned a new campaign, this time east into Macedonia. When Pyrrhus met with more success than he expected, the expedition turned from a limited raid into a full-scale invasion. After defeating Antigonus Gonatas, the king of Macedonia, at the
Battle of the Aous he conquered most of his kingdom. Antigonus held on to several coastal cities due to Pyrrhus' inability to take coastal cities because he lacked a strong fleet. Antigonus himself had a strong fleet and was able to reinforce and supply his coastal holding at will. Pyrrhus now wasted his victory. Taking possession of
Aegae, the ancient capital of Macedonia, he installed a garrison of Gaul mercenaries, who greatly offended the Macedonians by digging up the tombs of their kings and leaving the bones scattered about as they searched for gold. He also neglected to finish off Antigonus; leaving him in control of the coastal cities. In 272 BC,
Cleonymus, a Spartan of royal blood who was denied the throne, asked Pyrrhus to attack Sparta and place him in power. Pyrrhus agreed to the plan, intending to win control of the
Peloponnese for himself. Pyrrhus gathered an army of 25,000 infantry, 2,000 cavalry and 24 war elephants and invaded the Peloponnese under the ruse of attacking Antigonid garrisons in southern Greece. He then marched his army through allied country all the way to the south of Sparta and tried to take the city. Despite the majority of the Spartan army campaigning in
Crete, the remaining Spartans were able to mount a defence led by the Spartan prince
Acrotatus. The Spartans were able to withstand the Epiriote assaults until the arrival of the main Spartan army, led by King
Areus I, and Antigonid reinforcements from
Corinth, prompting Pyrrhus to abandon the siege. After this failure, Pyrrhus ravaged the Spartan hinterland whilst fending off counter-attacks by the victorious Spartans. His retreating army was continuously harried by the Spartans under the command of Areus. By setting
ambushes and occupying important positions along the Epiriote line of retreat, the Spartans were able to inflict significant casualties on Pyrrhus'
rearguard, killing his son
Ptolemy. Pyrrhus had little time to mourn, as he was immediately offered an opportunity to intervene in a civic dispute in Argos. He was approached by
Aristeas, the leader of the democratic faction in Argos, who sought support to counter the pro-Macedonian aristocratic party of Argos led by
Aristippus. ==Prelude==