[2] Demetrius was born in either 275 or 274 BC and was the only child of King Antigonus II Gonatas by Phila, the daughter of Seleucus I.

[4] He had already distinguished himself during his father's lifetime by defeating Alexander II of Epirus at Derdia and so saving Macedonia (c. 260 BC).

[5] During his reign, his kingdom extended[6]: 321  into Euboea, Magnesia, Thessaly and its environs, excluding Dolopia and possibly Peparethos and Achaea Phthiotis.

At some point in 230–229 BC in an unknown location in north-west Macedonia, the Dardani defeated Demetrius who died shortly the next spring at the age of c.

[9] His nine year old successor, the future Philip V, was deemed too young to rule by the Macedonian nobility and so Demetrius' half-cousin, Antigonus III Doson, was made regent.