Complex sentence: The IRB played an important role in the history of Ireland, as the chief advocate of republicanism during the campaign for Ireland's independence from the United Kingdom, successor to movements such as the United Irishmen of the 1790s and the Young Irelanders of the 1840s.
Split into simpler sentences: The IRB played an important role in the history of Ireland, as the chief advocate of republicanism during the campaign for Ireland's independence from the United Kingdom. Following on from movements such as the United Irishmen of the 1790s and the Young Irelanders of the 1840s.