Philip was born the son of King Demetrius II, but was adopted by Antigonus Doson, whom he succeeded as king in 221. He defeated the Aetolian League, Sparta and Elis in a war from 220 to 217 in alliance with the Achaean League. His later alliance with Demetrius of Pharos and then with Carthage precipitated the Macedonian Wars, and ultimately the Roman domination of Greece.