Catholic Church in Ireland
In the 2016 Irish census 78.3% of the population identified as Catholic in Ireland; numbering approximately 3.7 million people. Unlike Catholics in the United States, Ireland has seen a significant decline from the 84.2% who identified as Catholic in the 2011 census.
Oath of Allegiance (Ireland)
The Oath of Allegiance was also seen as a barrier to Catholics (and later Nationalists) in Ireland sitting in the House of Commons following the Act of Union. In 1828 following his victory in the election in County Clare, Daniel O'Connell refused to take the Oath of Allegiance to the British Crown. Following the granting of Catholic emancipation in 1829 and the dilution of the tones of religious supremacy, O'Connell took his seat in 1830 the first Irish Catholic to do so in the modern era.