Why is Ireland divided? | The significance and legacy of the Government of Ireland Act 1920

In this video made with and for the UK Parliamentary Archives we explore the partition of Ireland, implemented by the Government of Ireland Act 1920.

Clarification Note:
7.20: In fact, the immediate targets of the Unionist led move to drop Proportional Representation were smaller parties like the Northern Ireland Labour Party but the result remained the same. The dropping of PR helped strengthen the UUP’s hold on Northern Ireland Parliament, a state of affairs that excluded Nationalists from any decision-making throughout that Parliament's existence. While after the introduction of Direct Rule in 1972 it was generally accepted that Nationalists had to be included in any new system of devolved government, power-sharing did not become established until the Good Friday settlement.

Image credits:
0.02: Government of Ireland Act 1920 © Parliamentary Archives, HL/PO/PU/1/1920/10&11G5c67.
0.23: William Gladstone © Parliamentary Archives, PHO/7/1/45.
0.33: Charles Stewart Parnell © Parliamentary Archives, PHO/4/2/13 and John Redmond © Parliamentary Archives, PHO/4/2/13.
0.43: Herbert H. Asquith © Parliamentary Archives, PHO/4/2/2.
0.46: Government of Ireland Act 1914 © Parliamentary Archives, HL/PO/PU/1/1914/4&5G5c90.
0.58: Dublin Bread Company. Courtesy of the National Library of Ireland, KE118.
1.04: Abbey Street corner, Hibernian Bank shelled. Courtesy of the National Library of Ireland, KE115.
1.44: Sinn Féin election poster in 1918, quoting D. D. Sheehan MP, leading up to the December 1918 general election in Ireland. Public Domain.
1.56: Dáil Eireann, 21 January 1919. Public Domain.
2.05: Constance Markievicz. Courtesy of the National Library of Ireland, KE82.
2.28: Seán Hogan's (NO. 2) Flying Column, 3rd Tipperary Brigade, IRA. Public Domain.
2.45: The First Dáil Éireann taken at the Mansion House on the 21 January 1919. Public Domain.
2.52: A proclamation offering a reward of 1000 pounds for information leading to the capture of those involved in the Soloheadbeg shooting. Public Domain.
3.12: 'Relief', taken after an IRA attack on the London and North Western Hotel, Dublin. Courtesy of the National Library of Ireland, HOGW 117.
3.16: A Black and Tan on duty. Courtesy of the National Library of Ireland, HOGW 121.
3.22: A lorry load of Auxiliaries during the funeral of Major Holmes, RIC. Courtesy of the National Library of Ireland, HOG 155.
3.29: Military carrying out official reprisal following an ambush in Meelin, Co. Cork. Courtesy of the National Library of Ireland, HOG 156.
3.35: British soldiers marching out of a barracks. Courtesy of the National Library of Ireland, HOG 63.
3.41: Facade of Sunner's Pharmaceutical and Dispensing Chemist at 31 Patrick Street, Cork, destroyed by the Black and Tans. Courtesy of the National Library of Ireland, HOG 153.
3.54: Government of Ireland Act 1920 © Parliamentary Archives, HL/PO/PU/1/1920/10&11G5c67.
4.38: Sir Edward Carson signing the Ulster Solemn Covenant in Belfast City Hall on Ulster Day, 28th September 1912. Public Domain.
4.42: Unionist clubs marching down Donegall Square North in Belfast on 9 April 1912. Public Domain.
5.17: Union Theological College, site of the first Northern Ireland Parliament. Courtesy of the Principal of Union Theological College.
5.24: A crowd gathers outside the Mansion House, Dublin, 8 July, 1921. Courtesy of the National Library of Ireland, HOG 116.
5.32: Anglo-Irish Treaty, Irish Negotiators. Courtesy of the National Library of Ireland, HOG 3.
5.37: Vigil in Whitehall, 14 July 1921. Courtesy of the National Library of Ireland, HOG 1.
6.02: 1921 Evening Standard front page Signing of the Anglo-Irish Treaty - Image ID: H9N1F9. Alamy.
6.11: Proclamation of an Irish Republic, 1916. Public Domain.
6.21: The Four Courts in Dublin during the Battle of Dublin. The building had been taken over by Anti-Treaty forces on 14 April 1922. Bombarded by National Army forces on 28 and 29 June. Courtesy of the National Library of Ireland, HOG 57.
6.24: National Army troops lined up for a roll call during the Irish Civil War. Courtesy of the National Library of Ireland, HOG 121.
6.42: Éamon de Valera. Courtesy of the US Library of Congress.
7.05: Opening of the new Northern Ireland Parliament Buildings, Stormont, 16 November 1932. Courtesy of the National Library of Ireland, IND_H_2620.
7.15: Parliament Buildings, Stormont © Parliamentary Archives, PIC/P/716.
7.20: The Senate Chamber in the Parliament Buildings, Stormont, Belfast, 1956 © Parliamentary Archives, PIC/P/719.
7.26: The Commons Chamber, Parliament Buildings, Stormont, Belfast, 1956 © Parliamentary Archives, PIC/P/718.
7.39: Aerial view of Stormont, Belfast, showing the Parliament Building, Speaker's House and Stormont Castle. Jun 1973 © Parliamentary Archives, PIC/P/742.