On the morning of Nov. 21, 1920, Irish Republican Army agents, under orders from Michael Collins and Richard Mulcahy, executed multiple assassinations across Dublin in retaliation for British police actions in the city against members of the IRA. The attacks targeted British operatives and occurred in the area of south inner-city Dublin, except for two that took place at the Gresham Hotel. In total, 15 were killed: nine British Army officers, a member of the Royal Irish Constabulary, two members of the RIC’s Auxiliary Division, two civilians, and one man who was likely another British agent.
In retribution, British troops raided a Gaelic football game taking place in Croke Park at about 3:25 p.m. that afternoon. Close to 5,000 people were in the stadium to watch the match when British soldiers arrived in a convoy of trucks and armored cars. The soldiers were under orders to surround the park and search every man entering in an effort to locate the men who carried out the earlier assassinations. At some point they began firing into the crowd. Bullets flew for 90 seconds and some people were shot as they attempted to escape. Police on Canal Bridge opened fire on spectators who attempted to scale the Canal Wall to get away. By the time they were done shooting, seven people were dead. Five more would die of their wounds, while two others died from the crush of people trying to escape. Included among the dead were two boys, ages 10 and 11.
Later that night, two IRA officers, Dick McKee and Peadar Clancy, along with Conor Clune, were killed in Dublin Castle. The men had been in police custody and were being interrogated. Their guards claimed they shot them as the men tried to escape. However, autopsies showed the men had broken bones and abrasions and had been shot in the head and body. Multiple members of the IRA were rounded up and arrested in the days that followed Bloody Sunday. Two of them, Patrick Moran and Thomas Whelan, were sentenced to death and executed.