Year 288 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Tremulus and Arvina (or, less frequently, year 466 Ab urbe condita). The denomination 288 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Athens revolts and Demetrius besieges the city. Pyrrhus takes Thessaly and the western half of Macedonia and, with the assistance of Ptolemy's fleet, relieves Athens from Demetrius' siege.
After the Egyptian fleet participates decisively in the liberation of Athens from Macedonian occupation, Ptolemy obtains the protectorate over the League of Islanders, which includes most of the Greek islands in the Aegean Sea. Egypt's maritime supremacy in the Mediterranean in the ensuing decades is based on this alliance.
Following the death of Agathocles, some of his disbanded mercenaries seize Messana in northeast Sicily and set up a society, calling themselves Mamertines (Sons of Mars). The city becomes a base from which they will ravage the Sicilian countryside.