Irish Civil War
Conflict over the Anglo-Irish Treaty divided Irish society.
The Irish Civil War (28 June 1922 – 24 May 1923) broke out after the Irish War of Independence, as the Irish Free State—a self-governing dominion within the British Empire—was being established. The fighting pitted the Provisional Government of Ireland (which became the Free State in December 1922) against the Anti-Treaty IRA, who rejected the Anglo-Irish Treaty as a betrayal of the Irish Republic proclaimed during the 1916 Easter Rising. Many soldiers on both sides had fought together against the British in the Irish Republican Army during the earlier conflict, only to split after the treaty negotiations began.
The pro-treaty National Army won the war. They secured Dublin by early July 1922, then pushed into the anti-Treaty strongholds of the south and west—especially the so-called "Munster Republic"—capturing all urban centres by late August. A guerrilla phase lasted another ten months, until the IRA leadership ordered all units to "dump arms," effectively ending the conflict. The National Army’s success was aided by substantial British-supplied weapons, including artillery and armoured cars.
The war left Irish society deeply divided for generations. Today, the three largest political parties in Ireland trace their origins directly to the opposing sides: Fine Gael from the pro-Treaty supporters; Fianna Fáil, formed by Éamon de Valera from the bulk of anti-Treaty republicans; and Sinn Féin, from the minority of anti-Treaty republicans who refused to join any partitionist party.
**Background**
**Fallout of the Anglo-Irish Treaty** The Anglo-Irish Treaty ended the 1919–1921 Irish War of Independence between the Irish Republic and the United Kingdom. It created a self-governing Irish state with its own army and police, but allowed Northern Ireland—the six north-eastern counties (Fermanagh, Antrim, Tyrone, Derry, Armagh, and Down), where the majority population was Protestant—to opt out and rejoin the UK, which it did immediately. Partition triggered a two-year communal conflict within Northern Ireland. Instead of an independent republic, the Irish Free State became a British dominion, with the British monarch as head of state, like Canada and Australia. Britain had suggested dominion status in secret correspondence before negotiations, but Sinn Féin leader Éamon de Valera rejected it. The treaty also required members of the new Oireachtas (parliament) to
- start_date
- 28 June 1922
- end_date
- 24 May 1923
- location
- Ireland
- belligerents
- Provisional Government of Ireland (later Irish Free State) vs. Anti-Treaty IRA
- outcome
- Pro-Treaty National Army victory
- key_issue
- Anglo-Irish Treaty
Lore & Background
The civil war was waged between the Provisional Government of Ireland and the Anti-Treaty IRA over the Anglo-Irish Treaty. The Provisional Government (which became the Free State in December 1922) supported the terms of the treaty, while the anti-Treaty opposition saw it as a betrayal of the Irish Republic proclaimed during the Easter Rising of 1916. Many of the combatants had fought together against the British in the Irish Republican Army during the War of Independence and had divided after that conflict ended and the treaty negotiations began.
The Civil War was won by the pro-treaty National Army, who first secured Dublin by early July, then went on the offensive against the anti-Treaty strongholds of the south and west, especially the 'Munster Republic'. All urban centres had been captured by the National Army by late August. The guerrilla phase of the Irish Civil War lasted another 10 months, before the IRA leadership issued a 'dump arms' order to all units, effectively ending the conflict. The National Army benefited from substantial quantities of weapons provided by the British government, particularly artillery and armoured cars.
The conflict left Irish society divided and embittered for generations. Today, the three largest political parties in Ireland are direct descendants of the opposing sides in the war: Fine Gael, from the supporters of the pro-Treaty side; Fianna Fáil, the party formed from the bulk of the anti-Treaty republicans by Éamon de Valera; and Sinn Féin, comprising the minority of anti-Treaty republicans who refused to join any partitionist party.
Reader's Guide
The Irish Civil War was a defining conflict in modern Irish history, arising directly from the Anglo-Irish Treaty that ended the War of Independence. The treaty provided for a self-governing Irish state as a dominion of the British Empire, with an oath of allegiance to the British monarch and the partition of Ireland. These terms split the nationalist movement, with the pro-Treaty side arguing it offered freedom to achieve freedom, while the anti-Treaty side saw it as a betrayal of the Irish Republic. The war itself was brief but bitter, with the National Army quickly securing urban centers before a prolonged guerrilla phase. The conflict's legacy is profound: it left Irish society divided for generations, and the three largest political parties in Ireland today—Fine Gael, Fianna Fáil, and Sinn Féin—trace their origins directly to the opposing sides. The war also highlighted the deep personal and ideological rifts among former comrades, with figures like Michael Collins and Éamon de Valera on opposite sides. The National Army's use of British-supplied artillery and armored cars was decisive, and the eventual 'dump arms' order by the IRA leadership ended the fighting. The civil war's impact on Irish politics and society remains a central theme in understanding modern Ireland.
Did You Know?
- The Irish Civil War lasted from 28 June 1922 to 24 May 1923.
- The National Army benefited from substantial quantities of weapons provided by the British government, particularly artillery and armoured cars.
- The three largest political parties in Ireland today—Fine Gael, Fianna Fáil, and Sinn Féin—are direct descendants of the opposing sides in the war.
- The anti-Treaty opposition saw the Anglo-Irish Treaty as a betrayal of the Irish Republic proclaimed during the Easter Rising of 1916.
More in European Religious And Political Conflicts 1-19
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record