Irish Civil War (1922-1923): The Treaty Split in Ireland

The Irish Civil War was fought between June 1922 and May 1923 between the government of the new Irish Free State and republicans who rejected the Anglo-Irish Treaty of 1921. Former comrades of the Irish War of Independence turned on one another, and the conflict claimed the lives of leaders including Michael Collins. Its divisions shaped Irish politics for most of the twentieth century.

The Anglo-Irish Treaty

The Treaty was signed in London on 6 December 1921 by an Irish delegation led by Arthur Griffith and Michael Collins and by the British government of David Lloyd George. It created the Irish Free State, a self-governing dominion of the British Commonwealth like Canada, rather than the fully independent republic proclaimed in the Easter Rising and by the revolutionary Dail in 1919.

Members of the new parliament would have to swear an oath of fidelity to the king, Britain kept three naval bases, and Northern Ireland, already established in 1921, could opt out of the Free State. Collins argued in the Dail debates that the Treaty was not final freedom but gave Ireland the freedom to achieve it. Eamon de Valera, president of the Dail government, opposed it. On 7 January 1922 the Dail approved the Treaty by 64 votes to 57, and de Valera resigned.

The road to war

A Provisional Government under Collins took over Dublin Castle from the British in January 1922 and began to build a National Army. Much of the IRA, however, rejected the Treaty. On 14 April 1922 anti-Treaty fighters under Rory O’Connor and Liam Mellows occupied the Four Courts, the centre of Ireland’s legal system, in Dublin.

Attempts at compromise failed. In the general election of 16 June 1922 pro-Treaty candidates and other parties accepting the settlement won a clear majority. Days later, on 22 June, the British field marshal Sir Henry Wilson was shot dead in London, and the British government pressed Collins to act. When anti-Treaty forces kidnapped a senior National Army officer, the government decided to move against the Four Courts.

Course of the war

On 28 June 1922 the National Army began shelling the Four Courts with field guns lent by the British. The garrison surrendered on 30 June, after a huge explosion destroyed the Public Record Office and centuries of Irish archives. Fighting in central Dublin lasted about a week; the republican leader Cathal Brugha was mortally wounded on 5 July.

Anti-Treaty forces then held much of the south, sometimes called the “Munster Republic”. In July the National Army took Limerick and Waterford, and in August seaborne landings in Kerry and Cork outflanked the republicans, who abandoned Cork city by 10 August. The government suffered two heavy blows in quick succession: Arthur Griffith died of a brain haemorrhage on 12 August, and Collins was killed in an ambush at Beal na Blath in County Cork on 22 August.

W. T. Cosgrave took over as head of government. The war became a bitter guerrilla struggle of ambushes, raids and reprisals. Emergency powers allowed military courts to impose the death penalty, and the government officially executed 81 republicans between November 1922 and May 1923, among them Erskine Childers and, in December 1922, four imprisoned leaders including O’Connor and Mellows. Atrocities on both sides, such as the killings at Ballyseedy in County Kerry in March 1923, left lasting bitterness.

The anti-Treaty chief of staff, Liam Lynch, was killed on 10 April 1923. His successor, Frank Aiken, ordered a ceasefire at the end of April, and on 24 May 1923 republican fighters were told to dump their arms. There was no formal surrender or peace treaty.

Key people

• Michael Collins: Treaty negotiator, chairman of the Provisional Government and commander of the National Army.
• Eamon de Valera: political leader of the anti-Treaty side, though he had little control over its military campaign.
• W. T. Cosgrave: head of the Free State government from August 1922.
• Liam Lynch: chief of staff of the anti-Treaty IRA until his death.

Consequences and legacy

The Irish Free State came into formal existence on 6 December 1922 and survived its first test. Estimates of the dead range from about 1,500 to 2,000, a lower toll than many civil wars but devastating for a small society where opponents had often been friends or relatives. Thousands of republicans were interned.

The war’s two sides became the two main parties of independent Ireland. De Valera founded Fianna Fail in 1926 and entered the Dail, winning power in 1932; supporters of the Treaty formed Cumann na nGaedheal and later Fine Gael. This “Civil War politics” dominated Irish elections for generations. The partition of Ireland, by contrast, was confirmed in 1925, laying the ground for later conflict in Northern Ireland, including the Troubles.

Timeline

• 1921, 6 December: The Anglo-Irish Treaty is signed in London.
• 1922, 7 January: The Dail approves the Treaty by 64 votes to 57.
• 1922, 14 April: Anti-Treaty forces occupy the Four Courts in Dublin.
• 1922, 16 June: Pro-Treaty candidates win a majority in the general election.
• 1922, 28 June: The National Army shells the Four Courts; the war begins.
• 1922, 22 August: Michael Collins is killed at Beal na Blath, County Cork.
• 1922, 6 December: The Irish Free State is formally established.
• 1923, 10 April: Anti-Treaty chief of staff Liam Lynch is killed.
• 1923, 24 May: Republican fighters are ordered to dump arms.

Why it matters

The Irish Civil War decided that Ireland would follow the gradual path of the Treaty towards full independence, a goal largely achieved by 1949. It also left a legacy of division and silence that shaped Irish party politics and family memory for decades.