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The Anglo-Irish Treaty of 1921 stated that the 26 southern counties would form a de facto independent free state within the British Empire. Parts of the Irish society rejected the treaty and wanted a republic. Another point of dispute was that six counties of Ulster remained within the United Kingdom. Against this background the relatively short but very cruel Irish Civil War took place.






  • Date: 28 Jun 1922 – 24 May 1923
  • Location: Ireland
  • Start: Battle of Dublin
  • End: Aiken & de Valera order the IRA to lay down their weapons


Parties & Persons Involved

  • Irish National Army
  • Michael Collins (1890- 1922)
  • Richard Mulcahy (1886 - 1971)
  • Irish Republican Army
  • Liam Lynch (1893 - 1923)
  • Frank Aiken (1898 - 1983)
  • Eamon de Valera (1882 - 1975)



  • Southern Ireland gains its independence after the Irish War of Independence (1919 – 1921) & the Anglo-Irish Treaty (06 Dec 1921):
    • Ireland is a Free State within the British Empire
    • The English Monarch remains head of state
    • Northern Ireland remains a part of the United Kingdom
    • The Royal Navy remains control of 3 strategically important ports
  • 07 Jan 1922: The Dail Eireann ratifies the treaty by a small majority
  • Republican reaction:
    • de Valera resigns as president & gives speeches which (indirectly) demand a civil war: “[The IRA] would have to wade through the blood of the soldiers of the Irish Government...“
    • IRA officers reject the right of the parliament to ratify the treaty
  • 16 Jun 1922: The Pro-Treaty Sinn Fein (Collins) wins the election against the Anti-Treaty Sinn Fein (de Valera)
  • Michael Collins establishes the Irish Free State & the National Army
  • Distribution of power in June 1922:
    • Free State controls Dublin, cities & a small number of rural areas
    • IRA controls most of the rural areas



  • 14 Apr 1922: IRA men occupy Four Courts in Dublin
  • 16 Jun 1922: “Free State parties“ win the parliamentary election
  • 22 Jun 1922: The British government plans an intervention in Ireland & pressures Michael Collins after Irishmen murder Field Marshal Sir Henry Wilson
  • 28 – 30 Jun 1922: The National Army shells the IRA in Four Courts with British guns which leads to the surrender of the occupants
  • 01 – 05 Jul 1922: The Free State gains control over Dublin after bloody street battles

Initial Situation

Free State


Number of troops

Initially clear advantage for the IRA / changes during the conduct of the war


Veterans from the War of Independence & the World War

Mostly no or only small experience


Light & heavy weapons

Only light weapons

Control over

Esp. Dublin

  1. Munster


  • Jul – Aug 1922: The Free State takes the cities Cork, Limerick & Waterford & gains control over Counties Mayo & Kerry
  • 25 Jul – 05 Aug 1922: Free State wins the Battle of Kilmallock
  • Aug – Sep 1922: Extensive guerrilla warfare of the IRA
  • 22 Aug 1922: Michael Collins is killed during an ambush in County Cork
  • Sep – Dec 1922: Anti-guerrilla successes of the National Army & supply problems lead to a decrease of IRA attacks
  • Nov 1922 – May 1923: IRA assassinates representatives of the Free State & burns houses of politicians down
  • Nov 1922 – Ma 1923: Free State executes imprisoned IRA members
  • Jan – May 1923: Further Successes of the National Army & supply problems wear the IRA down
  • 24 May 1923: The military commander Aiken & the political leader de Valera call on the IRA to lay down the weapons


Consequences & Impact

  • Because the war focused on the southern part of Ireland Northern Ireland is consolidated as a part of the United Kingdom
  • The Irish Civil War is a short but extremely brutal war with war crimes on both sides
  • The 2 leading parties in Irish politics emerge from the Civil War
    • Pro-Free State - Fine Gael
    • Anti-Free-State - Fianna Fail
  • The Civil War & the resulting parties determine the Irish political life at least for decades