Antigonus II Gonatas
The war in Italy had drained Pyrrhus' financial and military resources. To increase his resources and bolster his standing, he declared war on King Antigonus II Gonatas of Macedon. He ravaged part of the country before managing to defeat Antigonus at the Battle of the Aous. This defeat compelled Antigonus to flee to Thessaloniki, where he was protected by his strong navy. Following Antigonus' flight, Pyrrhus was able to gain control of most of Macedon and Thessaly, declaring himself King of Macedon.