When war broke out in 1914 most nationalist and unionist leaders backed the British war effort, and Irishmen, Catholic and Protestant, enlisted in large numbers, many in three specially raised divisions. The war overlapped with the Easter Rising, and its memory in Ireland has long been divided. Here are the numbers as the sources give them, the units, the main events and some of the people.
| Figure | What it counts | Source |
|---|---|---|
| 27,405 | Irish deaths in the British Army recorded by the registrar general (a casualty rate of 14 per cent). | Wikipedia: Ireland and World War I |
| About 30,000 | died serving in Irish regiments of the British forces. | Wikipedia: Ireland and World War I |
| 29,450 | men born in, living in, or with next of kin in the 26 counties that became the Irish Free State, killed in British and Commonwealth forces (a study published in 2017). | Wikipedia: Ireland and World War I |
| About 40,000 | a confirmed all-Ireland toll, if that 2017 figure is added to another study’s 10,300 deaths for the counties that became Northern Ireland. | Wikipedia: Ireland and World War I |
| 49,400 | the figure on the National War Memorial at Islandbridge, Dublin. The article says it counts all deaths in the Irish divisions whether Irish-born or not, and that only 71 per cent of the casualties in those divisions were natives of Ireland. | Wikipedia: Ireland and World War I |
There is no single agreed total. The differences come from who is counted: Irish-born, Irish-resident, or anyone in an Irish unit.
Eight regular infantry regiments had recruiting areas in Ireland. When the Irish Free State was formed in 1922, the five whose areas lay in the south were disbanded. [source]
| Regiment | After 1922 |
|---|---|
| Royal Irish Regiment | Disbanded 1922 |
| Connaught Rangers | Disbanded 1922 |
| Prince of Wales’s Leinster Regiment (Royal Canadians) | Disbanded 1922 |
| Royal Munster Fusiliers | Disbanded 1922 |
| Royal Dublin Fusiliers | Disbanded 1922 |
| Royal Inniskilling Fusiliers | Continued in service |
| Royal Irish Rifles | Continued in service (listed as the Royal Ulster Rifles) |
| Princess Victoria’s (Royal Irish Fusiliers) | Continued in service |
Irishmen also served in the Irish Guards, Irish cavalry regiments, the North and South Irish Horse, the Liverpool Irish, the London Irish Rifles and many other units, as well as in dominion and US forces.
Raised largely from the Irish National Volunteers, the 10th was the first Irish division to take the field. Two of its brigades landed at Suvla Bay on 7 August 1915, part of the August offensive, while others fought at Chunuk Bair. Losses were very heavy. When the Suvla front stalled the division went to Salonika, and later to Egypt and Palestine.
Sources: Wikipedia: Ireland and World War I ↗ · Wikipedia: 10th (Irish) Division ↗ · Wikipedia: Landing at Suvla Bay ↗
Formed from the Ulster Volunteer Force, the 36th suffered 5,500 casualties on 1 July, 2,000 of them killed. Four of the nine Victoria Crosses awarded to British forces in the battle went to its soldiers.
Sources: Wikipedia: Ireland and World War I ↗ · Wikipedia: 36th (Ulster) Division ↗
The 16th, largely drawn from the National Volunteers, captured Guillemont on 3 September (the overview article says 2 September) and Ginchy on 9 September 1916, with very heavy casualties. Tom Kettle was killed at Ginchy.
Sources: Wikipedia: Ireland and World War I ↗ · Wikipedia: 16th (Irish) Division ↗ · Wikipedia: Battle of Guillemont ↗ · Wikipedia: Tom Kettle ↗
The 16th (Irish) and 36th (Ulster) Divisions advanced side by side on Wytschaete (Wijtschate) at the Battle of Messines (7–14 June 1917), which the main article calls the largest concentration of Irish soldiers on one battlefield. Major Willie Redmond MP, aged 56, brother of John Redmond, was killed on the first day; men of both divisions formed his guard of honour.
Sources: Wikipedia: Ireland and World War I ↗ · Wikipedia: Battle of Messines (1917) ↗ · Wikipedia: Willie Redmond ↗
The Military Service Act of April 1918 extended conscription to Ireland, linked by Lloyd George to Home Rule. A Mansion House conference met on 18 April, an anti-conscription pledge was taken at church doors on 21 April, and a one-day general strike followed on 23 April. The law was never put into effect and no one in Ireland was conscripted; the crisis boosted support for separatist parties.
The Kingstown–Holyhead mailboat was torpedoed by UB-123 four nautical miles east of the Kish light. Her log lists 77 crew and 694 passengers, nearly 500 of them military. The exact number of dead is unknown: researchers from the National Maritime Museum of Ireland believe it was at least 564, the largest single loss of life in the Irish Sea. 21 Post Office staff were among the dead.
Sources: Wikipedia: RMS Leinster ↗
A round tower near the site of the Messines fighting, unveiled by President Mary McAleese in the presence of Queen Elizabeth II and King Albert II of Belgium, in memory of soldiers from all of Ireland who died, were wounded or are missing in the war. It began as a project of Paddy Harte TD and Glen Barr.
Tom Kettle (1880–1916). Economist, barrister and Irish Parliamentary Party MP for East Tyrone (1906–1910). Killed with B Company, 9th Royal Dublin Fusiliers, near Ginchy on 9 September 1916. His sonnet ‘To My Daughter Betty, the Gift of God’ was written days before his death. A bust of him by Albert Power, finished in 1921, stands in St Stephen’s Green after a delay of almost twenty years. [source]
Francis Ledwidge (1887–1917). Poet from Slane, County Meath, ‘the poet of the blackbirds’, encouraged by Lord Dunsany. Although he had sided with the Volunteers who opposed the war, he enlisted in the Royal Inniskilling Fusiliers in October 1914. He was killed on 31 July 1917 in the early phase of the Battle of Passchendaele. His birthplace cottage has been a museum since 1982. [source]
Willie Redmond (1861–1917). MP for 34 years, killed at Messines on 7 June 1917 with the 6th Royal Irish Regiment. His grave at Loker (Locre) was left where it lay at his widow’s request. [source]
Sources put it at over 200,000 men from Ireland. One breakdown gives 206,000 in the British forces; another estimate is about 210,000 men and women, with more in other Allied armies.
Figures differ. The registrar general recorded 27,405 Irish deaths in the British Army; about 30,000 died in Irish regiments; a 2017 study and a Northern Ireland study together give about 40,000; the Islandbridge memorial says 49,400, a figure that includes non-Irish men in the Irish divisions.
No. A law extending it to Ireland was passed in April 1918 but never put into effect, after a campaign that included a church-door pledge and a general strike on 23 April 1918.
The exact number is unknown. Researchers at the National Maritime Museum of Ireland believe at least 564 died when she was torpedoed on 10 October 1918.
Wikipedia articles read October 2026, with the works they cite. Spotted an error? Tell us.