For “four glorious years” (as the republican publicity chief Frank Gallagher called his memoir of the period) of resistance to Britain between 1918–21, the Sinn Féin movement held together in pursuit of Irish independence. But immediately after the Anglo-Irish Treaty was signed on 6 December 1921, sharp divisions appeared.


The Irish representatives had been divided from the start of the treaty negotiations on issues of sovereignty and unity. The sides were broadly marked by those who were determined to uphold the sovereign republic declared in January 1919, and those who accepted that Britain’s refusal to give ground on the central issues of crown and empire meant that any agreement must involve modifying that independence.

Arthur Griffith, who founded Sinn Féin in 1905 and was the leader of the Irish delegation to London to sign the Anglo-Irish Treaty, was one of the latter. More surprisingly, Michael Collins – who as president of the Irish Republican Brotherhood (a role regarded by some as virtual president of the republic) was widely presumed to be a diehard republican – also became one as the negotiations went on.

A photo of Michael Collins and Arthur Griffith arriving at 10 Downing Street
Michael Collins (right) and Arthur Griffith (left) arriving at 10 Downing Street, London for the treaty negotiations between representatives of Sinn Fein and the British government in December 1921. (Photo by Central Press/Hulton Archive/Getty Images)

The treaty set aside the title ‘republic’ in favour of a ‘free state’ (a literal translation of the term ‘Saorstát’, officially used by the Irish parliament Dáil Eireann since 1919), with powers equivalent to the self-governing Dominions of the Empire.

January 1922: Sinn Féin splits

In reaction to the signing of the treaty, Eamon de Valera, president of the Dáil, moved to sack the signatories from his cabinet. One of his ministers, William T Cosgrave, instead persuaded him to hold a cabinet meeting and take a vote on the treaty. The cabinet approved it by a single vote, and a long and bitter debate began in the Dáil.

Accusations that the signatories, led by Arthur Griffith, had failed to refer the treaty back to Dublin before signing it, helped to poison the political atmosphere. But the issues at stake were more serious.

Eamon de Valera (right) and Arthur Griffith
Eamon de Valera (right) and Arthur Griffith. (Image by Getty Images)

Many Irish republicans believed that the republic, which had been declared at the first meeting of the Dáil in January 1919, was not a negotiating ploy but a real state, which could not be signed away without national dishonour. The concepts of honour and betrayal (of those who had died in the name of the republic) stalked the treaty debate.

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The final vote was won by those who accepted that the treaty – as Michael Collins put it – did not deliver “freedom” in the sense of outright independence, but the freedom to achieve it. Crucially, the treaty was all that could be wrung out of Britain at that point; idealism must be tempered with pragmatism, it was felt.

But the margin of victory was narrow – 64 to 57 – and that was further reduced when de Valera stood for re-election as president, losing to Griffith by just two votes. In response, de Valera and his supporters walked out of the Dáil.

February 1922: anti- and pro-treaty tensions build

Two governments were now in existence: the Dáil cabinet now headed by Griffith, and the Provisional Government set up under the treaty and headed by Collins. Both pushed for an early general election. De Valera and the Irish Republican Army (IRA) opposed such an election, fearing that it would be influenced by the same British pressure which they believed had forced the delegates to sign the treaty.

Sinn Féin tried to preserve a semblance of unity at its special Ard-fheis (party conference) in February 1922, resolving to delay the election until the new constitution had been drawn up. Hopes now rested on the ‘army of the republic’, the IRA, to hold together and find a way forward. Collins thought that his position as president of the Irish Republican Brotherhood (IRB) would make this happen, but though the IRB Supreme Council supported the treaty, it proved unable to persuade a large part of the army to follow suit.

Irish political activist Eamon de Valera speaks in front of a crowd
Irish political activist Eamon de Valera speaks in front of a crowd, c1922. (Image by Getty Images)

Powerful impulses against open division persisted, and the ‘Neutral IRA’, which aimed to keep the army together [and were against taking a pro- or anti-treaty stance], became the largest grouping in the army. But its efforts failed. When a proposed Army Convention in February was banned by Richard Mulcahy, the Free State government’s minister for defence, the convention went ahead anyway. Mulcahy described this as the IRA mutinying against the Dáil, and the situation began to look irretrievable. As the British army abandoned its garrison points across the country in line with the Anglo-Irish Treaty provisions, the barracks were occupied by whichever IRA group was locally strongest.

April 1922: the IRA seizes garrisons

In the strategically key city of Limerick, a direct clash between the pro- and anti-treaty forces in February was headed off with great difficulty. In mid-April the anti-treaty IRA raised the stakes by occupying buildings in Dublin, most notably the Four Courts – a formidable building with a substantial garrison commanded by Irish republican Rory O’Connor.

The remains of the Four Courts in Dublin, Ireland
The remains of the Four Courts in Dublin, Ireland, July 1922. (Photo by The Print Collector/Print Collector/Getty Images)

Britain became increasingly anxious that by tolerating this occupation, the Provisional Government risked sliding gradually into accepting the republican position. It subsequently pressured the Provisional Government to resolve the situation by force if necessary. An ‘electoral pact’ agreed by Collins and de Valera on 20 May, ensuring that the general election would reproduce the balance of pro- and anti-treaty members as in the treaty vote, further alarmed Britain.

But the eventual election in mid-June saw pro-treaty candidates win a substantial majority; no anti-treaty candidates headed the poll in any constituency.

June 1922: a political assassination sparks open conflict

On 22 June 1922, two IRA gunmen assassinated British Army Field-marshal Sir Henry Wilson in London because they believed that as security adviser to the Northern Ireland government, he was responsible for anti-Catholic violence in Belfast. Though the gunmen – Reginald Dunne and Joseph O’Sullivan, who were both Londoners – seem to have acted independently, the British government believed that the attack was ordered by Rory O’Connor and delivered an ultimatum to Collins to eject O’Connor from the Four Courts. Within a few days a military assault was launched, using artillery borrowed from the British army.

The fighting in Dublin in early July 1922 foreshadowed the war that followed. The anti-treaty IRA had no coherent strategy. Its attempt to bring in forces from the south-west to the capital stalled just outside Dublin; the republican force dispersed and reverted to guerrilla tactics. This was a heavy blow to the anti-treaty IRA’s hopes of disputing control of the country with the new National Army.

Irish Republican Army officers, including General Rory O'Connor, lined up in front of the Tricolour Flag
Irish Republican Army officers, including General Rory O'Connor, lined up in front of the Tricolour Flag. (Photo by Walshe/Topical Press Agency/Getty Images)

Elsewhere, the IRA – however experienced in guerrilla methods – proved unable to defend fixed positions against National Army forces armed with artillery (usually just a single field gun). Only eight National Army soldiers were killed when the republicans were driven out of Limerick later that month.

August 1922: decisive action from pro-treaty groups

In August 1922, the Free State government approach changed significantly. Griffith and Collins both died – the former of a reported heart attack and the latter killed in an ambush by anti-treaty forces. The so-called ‘civilian’ ministers – primarily William Cosgrave and Kevin O’Higgins, who had long called for more decisive action against the anti-treaty IRA – took control of strategy. The National Army was expanded, and offensives were launched across the country.

Liam Lynch, the republican chief of staff, together with Liam Deasy, commander of the IRA’s 1st Southern Division, hoped to set up a defensive line running from Limerick to Waterford. Though Deasy fought a long and skilful battle around Kilmallock, most republican defenders failed to stand against the Free State forces. These were often no more competently led than their opponents, but they had a few commanders – like John T Prout in the southwest and Emmet Dalton in Dublin – who, with their experience of commanding regular units in the First World War, successfully organised a series of seaborne landings to seize southwestern ports.

Free State soldiers camped outside the Four Courts Hotel in Dublin
Pro-treaty Free State soldiers use British artillery to attack the anti-Treaty Republican army who established their headquarters in the Four Courts in Dublin during the Irish Civil War. (Photo by Walshe/Getty Images)

Meanwhile, no credible republican government was set up; de Valera remained a marginal figure with no influence over the IRA, despite his huge prestige. The Free State government exploited the June election to insist that it represented the legitimate national will against what it labelled an anti-democratic militarist, or merely criminal, insurrection.

The press was instructed never to call republican forces ‘IRA troops’, but ‘irregulars’, ‘bands’ or ‘bodies of men’.

December 1922–March 1923: key republicans executed – without trial

In early December 1922, Seán Hales, a leading pro-treaty TD [Teachta Dála, member of the Dáil], was assassinated by two anti-treaty gunmen in early December 1922. The killing was used as pretext for the execution of Rory O’Connor and three other Four Courts leaders by firing squad on 8 December – without trial.

This effectively terrorist policy extended to local level, where Free State troops outdid the ‘Black and Tans’ (British reinforcements for the Royal Irish Constabulary recruited in 1920) in vicious violence.

The massacre of 23 republican prisoners at Ballyseedy by Free State forces in Kerry in March 1923 (five others were also judicially executed) was perhaps the worst, but it was hardly an isolated instance.

April–May 1923: a final blow leads to the conclusion of fighting

Meanwhile, Free State leaders Cosgrave and O’Higgins wanted a decisive victory rather than a negotiated settlement, and their demand that the IRA should surrender and decommission its weapons ensured that there was no negotiation.

The war went on partly because republican leaders remained optimistic, despite the steady deterioration of their position, that the nation would recognise the rightness of their cause.

But when Liam Lynch, IRA chief of staff, was killed in action on 10 April 1923, those pressing for abandonment of the fight took over.

The order to dump arms was finally issued on 24 May 1923.

What is the legacy of the Irish Civil War?

Civil wars inevitably leave a bitter legacy, and Ireland’s was no exception. But Ireland was unusual in the speed and success with which constitutional politics were restored in the later 1920s.

After de Valera returned to the Dáil in 1927 (taking the very oath which had sparked the civil war), his party, Fianna Fáil, and the Treaty party, Cumann na Gael (which in 1933 became Fine Gael) dominated Irish politics for the rest of the 20th century.

Against expectations, proportional representation – as imposed by Britain – produced largely majority governments. Ireland had many problems, but stability was not one of them.


Charles Townshend is Professor Emeritus of International History at Keele University. His latest book is The Partition: Ireland Divided, 1885–1925 (Allen Lane, 2021)