Anglo-Norman invasion of Ireland
The Anglo-Norman invasion of Ireland took place during the late 12th century, when Anglo-Normans and Cambro-Normans gradually conquered and acquired large swathes of land in Ireland over which the monarchs of England then claimed sovereignty. The Anglo-Normans claimed the invasion was sanctioned by the papal bull Laudabiliter.
Source: Wikipedia — Anglo-Norman invasion of Ireland (CC BY-SA 4.0)