Antigonus III Doson
When the peace talks failed, Aratus sent envoys to the Macedonian King, Antigonus III Doson, seeking military assistance. Antigonus pledged to give aid on the term that the formidable citadel, Acrocorinth was ceded to Macedon. This conditions elicited a furious response from many Achaeans and Cleomenes used this to his advantage by occupying the major cities of Corinth and Argos and many smaller settlements. Aratus accepted the terms proposed by the Macedonians and additionally surrendered the cities of Orchomenus and Heraia to Macedon. Subsequently, Antigonus mustered his army for the invasion of the Peloponnese.