In late January of 1972, the Prime Minister of Northern Ireland took a risk: he banned all protest demonstrations. Parades had been the starting points of several clashes during the long conflict over Britain's role in the region, and it seemed like ending them couldn't hurt—at first. "There were some suggestions that the I.R.A., for its part, might try a new tactic by organizing illegal parades of Catholics to test the ban and the government's will," TIME reported. "The result might well mean more bloody clashes between the warring sects, the need for still more British troops to maintain order, and more trouble for a land that has trouble enough."
As shown in this exclusive clip from the next episode of CNN's The Seventies, which airs on Thursday at 9 p.m. E.T., the prediction that the parade ban would not put an end to violence quickly proved correct. In fact, the violence that followed shortly after the ban was one of the best-known incidents of the period: Bloody Sunday.
On Jan. 30, 1972, a Catholic protest over the imprisonment of I.R.A. suspects turned violent, as TIME reported the following week:
On that bright, wintry afternoon, a march in the Catholic ghetto of Londonderry called the Bogside suddenly turned into a brief but violent battle between the marchers and British troops. When the shooting stopped, 13 people lay dead in one of the bloodiest disasters since the "troubles" between Ulster's Protestant majority and Catholic minority began almost four years ago. The incident seemed to end almost all hope of a peaceful settlement in Northern Ireland . Not since the executions that followed Dublin's 1916 Easter Rising have Catholic Irishmen, North and South, been so inflamed against Britain and so determined to see Ireland united in one republic at last.
Read more from 1972, here in the TIME Vault: The Bitter Road from Bloody Sunday