Corranmore, County Leitrim: A Landscape of Poverty and Memory
John Joseph MacDermott — later Seán Mac Diarmada — was born on 27 January 1883 in the townland of Corranmore, near the village of Kiltyclogher in the hills of County Leitrim, the son of Donald MacDermott, a carpenter and small farmer, and his wife Mary McMorrow. Leitrim was one of the poorest and most rural counties in Ireland, a place where the physical landscape carried the marks of the Famine — abandoned cabins, overgrown fields, the ghost of a pre-1845 population — and where the memory of oppression was maintained not by formal political organisation but by the stories told by schoolteachers to their pupils. Mac Diarmada's national schoolteacher, Master P. McGauran, gave the boy books on Irish history and instilled in him the republican understanding of Ireland's past that his father's IRB membership reinforced at home. Donald MacDermott had himself been a Fenian — a member of the IRB in an earlier generation — and the household was one where the cause of Irish freedom was not an abstraction but a family inheritance.
Mac Diarmada was educated at Corradoona National School and studied in the evenings at night school in Tullinamoyle, just across the County Cavan border, where he learned bookkeeping, shorthand, and Irish. He tried briefly to qualify as a teacher but failed the mathematics examination. He worked as a gardener for a short period in Edinburgh, then moved to Belfast in 1905, where he took employment as a tram conductor — an occupation common among young men from rural Ireland who sought work in the industrial north — and embarked on the political career that would define the rest of his short life.
The IRB: From Tram Conductor to National Organiser
In Belfast, Mac Diarmada joined the Gaelic League and the Dungannon Clubs — cultural and political nationalist organisations being built by Denis McCullough and Bulmer Hobson — and in 1906 was sworn into the Irish Republican Brotherhood by Denis McCullough. The IRB at the time was a declining organisation, its membership ageing, its structures atrophied by decades of inactivity and demoralisation following the failed Fenian campaigns of the nineteenth century. Mac Diarmada, working in concert with McCullough and Hobson, helped begin its revival from within the north.
In 1907 he moved to Dublin and came under the influence of Thomas Clarke — the veteran Fenian who had spent fifteen years in British prisons and had returned to Dublin in 1907 to build a new revolutionary movement from the tobacconist's shop on Great Britain Street that served as his base of operations. Clarke and Mac Diarmada became the most important political partnership in pre-1916 Irish republicanism: Clarke the master strategist, Mac Diarmada the master machinist. By 1908 Mac Diarmada was appointed full-time national organiser of the IRB, paid a salary to do nothing but travel the country, recruit members, and build the network of trusted men in every county who would eventually be the core of the 1916 mobilisation. He also became commercial manager of Irish Freedom, the IRB's newspaper, and helped to infiltrate the Gaelic League and the GAA, engineering the election of IRB men to their committees in order to extend the organisation's influence through the cultural nationalist movement.
The travelling was prodigious. Over several years Mac Diarmada cycled thousands of miles across Ireland — in the days before the motor car was common, this meant long journeys on rough roads, in all weather, arriving in provincial towns where he would meet local nationalist figures, assess their reliability, and where appropriate recruit them to the IRB. He carried a card-index of contacts in his head that was the organisational foundation of everything that followed. Michael Collins, who met Mac Diarmada in 1915 and who modelled his own IRB organising on what Mac Diarmada had built, cited him as the most important influence on his own approach. The network Mac Diarmada built was the network Collins inherited and used to direct the War of Independence.
Polio, Imprisonment, and the Military Council
In the autumn of 1911, Mac Diarmada contracted polio. He was hospitalised for several months and emerged permanently lame in one leg, thereafter needing a walking cane to move. The disability did not slow him perceptibly. He continued organising with the same energy, and was one of the founding members of the Irish Volunteers in November 1913, working to ensure that IRB men held key positions within the new organisation. When the First World War broke out in August 1914 and John Redmond pledged the Volunteers to the British war effort at Woodenbridge — an act that split the organisation and aligned the majority with the constitutional nationalist cause — Mac Diarmada was among those who rejected Redmond's position and maintained the smaller, more radical Irish Volunteers as a separate force.
In May 1915 he was arrested in Tuam, County Galway, and charged under the Defence of the Realm Act with making a speech discouraging Irishmen from joining the British Army. He spent four months in Mountjoy Prison and was released in September 1915. Immediately on his release he was co-opted, alongside Thomas Clarke, onto the IRB's secret Military Council — the small body planning the armed uprising. It was a body whose existence was concealed even from most IRB members. Mac Diarmada brought to it the most comprehensive knowledge of the organisational landscape of Irish republicanism of any man alive: he knew the personnel, the politics, the capabilities, and the reliability of Volunteer and IRB units across the country with an intimacy that no one else could match. The historian F.X. Martin characterised him as the mainspring of the Rising, a judgment echoed by almost every subsequent scholar.
Planning the Rising: Secrecy as Method and Liability
Mac Diarmada's method was obsessive secrecy — a response to what he understood as the fatal vulnerability of previous Irish rebellions, which had been penetrated by British informers at every level. He excluded not only ordinary IRB members but major figures — including Éamon de Valera, a Volunteer commandant and IRB member, and Eoin MacNeill, Chief of Staff of the Irish Volunteers — from knowledge of the Military Council's plans until the very final stages. This secrecy served its purpose in preventing British intelligence from discovering the plot in time to prevent it; it also produced the chaotic communications failures that undermined the Rising's military effectiveness.
MacNeill's countermanding order — issued on Easter Sunday morning when he finally discovered the extent of the Military Council's subterfuge and the loss of the German arms ship Aud — cancelled Volunteer mobilisation across the country and reduced the Rising to Dublin and a handful of other locations. Mac Diarmada's own response to the countermand was characteristically decisive: he sent messengers across the city on Easter Sunday night to contact Volunteer commandants directly and reverse MacNeill's order as far as possible. He also, in a pre-emptive move on Good Friday, had Bulmer Hobson — who he feared would warn MacNeill and abort the Rising — detained at a safe house for the duration of the critical period. These were not the actions of a man who made his decisions lightly or who underestimated the stakes. He told associates in the months before the Rising that the Irish patriotic spirit would die forever unless a blood sacrifice was made in the next few years. He offered himself as the sacrifice willingly.
Easter Week in the GPO
On Easter Monday, Mac Diarmada arrived at the General Post Office by motor car — his disability made the bicycle and foot approaches used by most of the garrison impractical — alongside Thomas Clarke, the two old conspirators finally seeing the work of years made flesh. Witnesses at the GPO described him as radiantly happy. A Volunteer named Ignatius Callender recorded looking across the floor of the Post Office at Mac Diarmada on Easter Monday and thinking: there's a happy man, for he surely looked the very picture of happiness, surrounded by the brave lads making a fight against the common enemy. As the week progressed and Connolly was wounded, Plunkett was ill, and Pearse retreated into himself, Mac Diarmada increasingly directed the practical conduct of the garrison — moving men, organising supplies, maintaining communication between positions. He was the last man in the burning GPO to accept that surrender was necessary. After the evacuation to Moore Street, it was Mac Diarmada who read out the surrender order to the garrison.
After the surrender, as the prisoners were marched through the streets, a British Army captain named Percival Lea-Wilson — later killed by the IRA during the War of Independence, in part for this act — made Clarke, Mac Diarmada, and Ned Daly strip to the skin in front of their comrades and three nurses. He then took Mac Diarmada's walking cane, forcing the lame man to keep pace with the other prisoners without it on the march to Richmond Barracks. The act was noted by a young captain named Michael Collins, who was present in the crowd of prisoners and who never forgot it.
Execution: The Last Two
Mac Diarmada was court-martialled on 9 May 1916 and mounted a vigorous defence, arguing that as a civilian member of the Provisional Government without military rank he should not be subject to military courts. The argument failed. He was sentenced to death. His closest friend and companion in all the years of planning was Thomas Clarke, executed on 3 May. His romantic attachment, Josephine Mary Ryan — Min Ryan, a Cumann na mBan activist and National University of Ireland graduate — and her sister were his last visitors, seeing him in Kilmainham in the hours before his death. He wrote in his final statement: I feel happiness the like of which I have never experienced. I die that the Irish nation might live.
Seán Mac Diarmada and James Connolly were the last of the fifteen executed leaders to die, both shot in the early hours of 12 May 1916. Connolly, who had been wounded during the Rising, was brought to the yard in a chair and shot sitting upright. Mac Diarmada walked to the yard with his cane. They died within minutes of each other, and their executions — the last of the series — marked the end of the British government's deliberate, systematic killing of the Rising's leadership. They were buried, like the others, in quicklime at Arbour Hill.
Legacy: The Mainspring Unmoved
Seán Mac Diarmada is among the less-celebrated of the seven signatories of the Proclamation, consistently overshadowed in popular memory by Pearse, Connolly, and Michael Collins — none of whom could have done what they did without the network Mac Diarmada spent a decade building. Michael Collins said explicitly that Mac Diarmada was his model. The IRB's post-1916 reorganisation, which Collins directed with the same methods of secrecy, penetration of cultural organisations, and personal recruitment that Mac Diarmada had pioneered, was a direct continuation of what Mac Diarmada had started. The intelligence network that won the War of Independence was built on the foundation Mac Diarmada had constructed.
He is commemorated in his native County Leitrim with a statue at Kiltyclogher, inscribed with his final words, and a national monument at his childhood home in Corranmore. Mac Diarmada railway station in Sligo, Páirc Seán Mac Diarmada in Carrick-on-Shannon, and Seán MacDermott Street in Dublin all carry his name. The Dictionary of Irish Biography summarises his role with characteristic academic restraint: as Clarke was the master mind, Mac Diarmada was the master machinist, the man who more than any other assembled and manipulated the various cogs of organisation. That is, in its way, the highest tribute that can be paid to a revolutionary: not that he dreamed the dream, but that he made it possible for the dream to happen.