Why did the British army go into Croke Park on 21st November 1920?

Answer It was an act of retaliation for killings of British agents earlier that day. 14 people were killed in Croke Park, including the captain of the Tipperary Hurling team, Michael Hogan. The Hogan Stand in Croke Park is named after him. Answer The British Army didn't go into Croke Park they were used to surround it. The Police, the Royal Irish Constabulary (RIC) and specifically the Auxiliaries (sometimes confused with the Black and Tans who were a separate organisation) were the ones who entered the grounds and started firing. Crown forces or British Forces is a term sometimes used so the assumption is it was the Army. The official explanation is the crowd were due to be searched for weapons after an announcement but before this could take place the Police opened fire. Subsequent claims they were fired on first have never been proven and only one revolver was recovered afterwards. Examinations of the bullets used on the victims showed they came from police rifles and pistols. The only shots fired by the Army were from an Armoured car outside the stadium over the heads of the crowd in an effort to control them (ignore the Hollywood version in Michael Collins). The Army officers in the subsequent enquiry were severely critical of the lack of control and discipline of the auxiliaries and Major Mills commanding them admitted they were "excited and out of hand", by the time he regained control the police and auxiliaries had expended 114 rounds of rifle ammunition as well as a quantity of revolver rounds. However eye witnesses have blamed the ordinary police rather than the auxiliaries for most of the shooting. The day became known as "Bloody Sunday" (also later used as a name for the 1972 shooting by Paratroopers of Civilians in Northern Ireland) for both the deaths at Croke Park and the killing of the British Agents. 31 died in total - 14 agents, 14 civilians and 3 IRA prisoners.