The Irish Unification of 2024 was an event in Earth history taking place in Ireland. It resulted in the creation of a unified Ireland, which until that point was a divided nation-state. This unification came about due to the use of terrorism rather than peaceful acts to bring about political change.
In 2366, the Irish Unification was noted by Lieutenant Commander Data as one of the numerous examples where terrorism was successfully used to bring about change. Other examples he listed were the independence of Mexico and the Kenzie Rebellion. (TNG: "The High Ground")
Due to political sensitivity, the reference to Irish unification and terrorism in "The High Ground" resulted in the latter episode's removal from first-run. To date, some syndicating networks will not air the episode, and it was only in 2007 (fifteen years after its first run, nine years after the conflict ended in a peaceful manner) that it was broadcast on BBC.