Bloody Sunday (1921) all had been killed or fatally wounded in Belfast. At the time the day was referred to as "Belfast's Bloody Sunday". However the title of "Bloody Sunday", is now more commonly given in Ireland to events in Dublin in November 1920 or Derry in January 1972. A strict curfew was enforced in Belfast after the violence, to try to ensure the Orange Order's 12 July marches passed off peacefully. Directly after the violence, on 11 July, the Commandant of the IRA's 2nd Northern Division, Eoin O'Duffy, was sent to Belfast by the organization's leadership in Dublin to liaise with the
Sunday football in Northern Ireland football on Sundays was strictly enforced so that no club affiliated with the IFA could play football in Northern Ireland on Sundays. This included the Northern Ireland national team who also refused to play international matches on Sunday. Before the 1958 FIFA World Cup, it was noted that Northern Ireland would play Czechoslovakia on a Sunday. As a result, the IFA relaxed its Sunday football ban to permit the Northern Ireland national team to play football on Sundays outside of Northern Ireland. In 2001, Cliftonville attempted to play a friendly match against Derry City, who are based in County Londonderry