The "Belfast Pogrom" begins two years of violence with the expulsion of thousands of Catholic shipyard, factory and linen mill workers from their jobs.

The Troubles in Ulster of the 1920s was a period of conflict in the Irish province of Ulster, from June 1920 until June 1922, during and after the Irish War of Independence and the partition of Ireland. In Ulster, it was mainly a communal conflict between unionists, who wanted to remain part of the United Kingdom, and nationalists, who backed Irish independence: the unionists were mainly Ulster Protestants and the nationalists were mainly Irish Catholics. During this period, more than 500 people were killed in Belfast alone, 500 interned and 23,000 people were made homeless in the city, while approximately 50,000 people fled the province due to intimidation. Most of the victims were Nationalists (73%) with civilians being far more likely to be killed compared to the military, police or paramilitaries.

The Catholic Church in Ireland, or Irish Catholic Church, is part of the worldwide Catholic Church in communion with the Holy See. With 3.5 million members, it is the largest Christian church in Ireland. In the Republic of Ireland's 2022 census, 69% of the population identified as Roman Catholic. By contrast, 41% of people in Northern Ireland identified as Catholic at the 2011 census, increasing to 42.3% in 2021.

July 21 is the 202nd day of the year in the Gregorian calendar; 163 days remain until the end of the year.