The dynasty founded by Antigonos Monophthalmos began in essence with his grandson Antigonos Gonatas.
After the destructive Gaulish incursions of 279-276 BC, Antigonos Gonatas used the occasion of his victory over the Gauls near Lysimacheia, Thrace to be proclaimed king of Macedonia. His goal was the economic recovery and population growth of the Macedonian kingdom, and the securing of its possessions in southern Greece (Demetrias, Chalkis, Corinth, possibly also Piraeus).
The Macedonian phalanx
Having countered Pyrrhos, the king of Epirus, he defeated the allied forces of Athens, Sparta, several Peloponnesian states and Ptolemy II, the king of Egypt (Chremonidean War, 267-261 BC). Antigonos seized the naval supremacy of the Aegean from the Ptolemies thanks to his naval victories at Andros and Kos.
He was not able, however, to prevent the Achaian League from reinforcing its positions and annexing Corinth and its strategically important acropolis (Acrocorinth). Antigonos Gonatas died one or two years later (240 or 239 BC) without having succeeded in recapturing it.