Chremonidean War 267 BC - 261 BC was fought by a number of Greek states against Macedon domination.

The origins of the war lie in the continuing desire of many Greek states, notably Athens and Sparta, for a restoration of their former independence along with Ptolomaic desire to create troubles for its rival Macedon. Ptolemy Philadelphus's ambitions in the Aegean were threatened by Antigonus Gonatas's fleet and so carefully built up a coalition against Macedon in Greece. He especially cultivated Athens, supplying with grain.

The anti-Macedon faction in Athens, led by the stoic Chremonides, took power and war was declared against Macedon (possibly as early as the autumn of 268 BC). The campaign season of 266 BC was indecisive but in 265 BC Antigonus won a decisive victory outside Corinth in which the Spartan King Areus I fell.

After that Athens was besieged and it was finally starved into surrender in either 262 BC or 261 BC. Philadelpus had failed to send aid to Athens and his fleet was defeated off Cos (probably in 261 BC).

After the fall of Athens, she lost all vestiges of independence and was permanently garrisoned.

Reference

Peter Green :Alexander to Actium