In 429 BC, Perdiccas II sent aid to the Spartan commander Cnemus in Acarnania, but the Macedonian forces arrived too late to enter the Battle of Naupactus, which ended in an Athenian victory. In that same year, Sitalces, according to Thucydides, invaded Macedonia at the behest of Athens to aid them in subduing Chalcidice and to punish Perdiccas II for violating the terms of their peace treaty. However, given Sitalces' huge Thracian invading force (allegedly 150,000 soldiers) and a nephew of Perdiccas II that he intended to place on the Macedonian throne after toppling the latter's regime, Athens must have become wary of acting on their supposed alliance since they failed to provide him with promised naval support. Sitalces eventually retreated from Macedonia, perhaps due to logistical concerns: a shortage of provisions and harsh winter conditions.