The polarised political climate in Northern Ireland resulted in violence from both sides of the political and religious divide . The lawlessness that affected Northern Ireland in the period of the early 1920s , and the problems it caused for the police , are indicated in a police report drawn up by District Inspector R.R. Spears in February 1923 . Referring to the situation in Belfast after July 1921 he stated : For twelve months after that , the city was in a state of turmoil . The IRA ( Irish Republican Army ) was responsible for an enormous number of murders , bombings , shootings and incendiary fires . The work of the police against them was , however , greatly hampered by the fact that the rough element on the Protestant side entered thoroughly into the disturbances , met murder with murder and adopted in many respects the tactics of the rebel gunmen . In the endeavour to cope simultaneously with the warring factions the police efforts were practically nullified . They were quite unable to rely on the restraint of one party while they dealt with the other . About 90 police officers were killed between 1920 and 1922 in what would become Northern Ireland . The security forces were implicated , but no convictions ever rendered , in reprisal killings of Catholics , notably the McMahon killings on 26 March 1922 in which six Catholics were killed , and the Arnon Street killings , several days later on 1 April 1922 , in which six more Catholics were shot dead in retaliation for the IRA killing of a policeman
McMahon killings
McMahon killings
Royal Ulster Constabulary