Seán MacMahon (born John Michael McMahon, ; 15 September 1893 – 26 March 1955) was an Irish nationalist who fought in the 1916 rising as captain of "B" Company, 3rd Battalion, Irish Volunteers, under Éamon de Valera. He later became quartermaster-general of the IRA. MacMahon took the pro-treaty side in the Irish Civil War (1922–23) and rose to be chief of staff of the Irish Defence Forces. He was also president of the Irish Republican Brotherhood.
Early life McMahon was born on Friday 15 September 1893 at 118 Cork Street in Dublin. His mother was Mary, formerly Delaney, and his father, Edward McMahon, was almost 25. He was the eldest of 7 children, with 4 brothers and 2 sisters: Pat (Patrick) born 23 July 1897, the twins Ned (Edward) and Tom (Thomas) born on 4 December 1902 and Joe (Joseph) born 7 July 1909. The girls were Annie, born 21 September 1895 and Kathleen (Catherine) born 9 November 1900.
After leaving school on 26 September 1907, just 11 days after his 14th birthday, MacMahon started work in Dublin Post Office. He left on 17 September 1909, having reached the age limit of 16.
He then turned to clerical work, perhaps at Plunkett Brothers where his father worked, for he gave 5 Sandwith Street as his address when later interned in 1916.
Revolutionary activities Irish Volunteers and Easter Rising
At the inception of the Volunteers in 1913 MacMahon was enrolled as a member of "B" Company, 3rd Battalion, Dublin City Brigade, at 144 Great Brunswick Street (now Pearse Street). In 1914 he became 1st lieutenant under The O'Rahilly with promotion to captain, replacing The O'Rahilly in 1915.
He represented "B" Company at a meeting of the battalion council on the Good Friday prior to the rising. Present were de Valera, Captain Begley, Lieutenant Byrne, Lieutenant Charlie Murphy and Joseph O'Connor. They were given precise orders as to the positions they were to occupy on the Sunday. They were informed as to the quantity of stores at their disposal. A large quantity of provisions had been purchased. Each company was to be responsible for the collection of such stores and their transport to their operational area. MacMahon was given responsibility for Westland Row train station. His company was to take over Westland Row Railway Station and send a party up to Tara Street to link up with 2nd Battalion in the Amiens Street section of the railway. They were on the other side to connect up with "A" Company on the railway at Grand Canal Quay.When The Clock Struck in 1916. Close-Quarter Combat in the Easter Rising. By Derek Molyneux and Darren Kelly. Witness Statement of Joseph O Connor. Bureau of Military History 1913 – 1921. Document Number WS 157
B Company cleared, barricaded and locked Westland Row station, cut telephone wires and seized signal boxes. They were charged to snipe and fight running battles around the railway so as to maintain control of it. Ensuring that any reinforcements landing at Kingstown (Dún Laoghaire) would have to march to Dublin. MacMahon then sabotaged part of the line and entrenched his men about 300 yards away from the station. As the railway ran through de Valera's command area, MacMahon was one of the two "best officers" to whom its defence was entrusted.The Easter Rising by Michael Foy and Brian Barton. Published by Sutton Publishing Ltd in 1999.
On Monday near Bath Avenue MacMahon and seven of his men repelled soldiers from Beggars Bush Barracks and killed a sergeant major. The Volunteer marksmen attacked British soldiers from behind the nine stone archways between Westland Row and Ringsend and shot at them on Great Brunswick Street and Grand Canal Street, as well as in the square of Beggars Bush Barracks. When one of his own men was seriously wounded, MacMahon took him to St Vincent's Hospital himself while in uniform and under fire from the British troops.
Towards the end of the fighting de Valera, based in Boland's Mill, ordered the burning of Westland Row station but was persuaded by MacMahon not to do so: it would have most likely led also to the burning of St Andrews Church next door on Westland Row. This story is passed down through the MacMahon family: "By Thursday/Friday he was exhausted: 'I can't trust the men – they'll leave their posts if I fall asleep, if I don't watch them. 'When Lt James Fitzgerald assured his O/C he'd sit by him de Valera relented and fell asleep immediately. Soon he awoke screaming. 'set fire to the railway!"1916 The Easter Rising by Tim Pat Coogan. Published in paperback by Phoenix (Orion Books) (page 118) De Valera insisted that papers be dipped in whiskey and used to set fore to the waiting rooms and rolling stock, but another officer, Cpt John Mc Mahon, O/C of B Company, 'eventually persuaded de Valera to reason and the fires were put out.Dublin in Rebellion A directory 1913 – 1923 by Joseph E.A. Connell jnr. Published by The Lilliput Press Dublin Revised edition 2009.
After the surrender of the garrison in Boland's Mills, the reaction by local people was unlike that of most other areas. They were friendly and sympathetic and the defeated men received an ovation in Grand Canal Street with offers of refuge. They were met by British officers and soldiers in Grattan Street, where they laid down their weapons. The men marched into Lower Mount Street through lines of bayonets.
MacMahon was imprisoned first in Wakefield then Frongoch, where he was listed as John McMahon, 5B Sandwith Street, and finally Wormwood Scrubbs. Leo, Thomas and James Fitzgerald of 173 Great Brunswick Street (Pearse Street), his future brothers-in-law, were also interned in Frongoch as were Michael Collins and Richard Mulcahy.The Irish Republican Brotherhood was also being reorganised in Frongoch.Frongoch University of Revolution by Sean O’Mahony. Published by FDR Teoranta 1987
In September it was suggested that a patch of ground be cultivated. MacMahon and two others, "being city men," asked to be shown how to do it and eventually admitted: "Put us in the clink we won't be doing any work".Frongoch University of Revolution by Sean O’Mahony. Published by FDR Teoranta 1987 MacMahon was one of 15 hut leaders court-martialled after the Murphy incident of 2 November. He was defended by Gavin Duffy and sentenced to 28 days hard labour, but served only six.
After the British government amnesty he arrived home on Christmas Eve 1916 via Dún LaoghaireFrongoch University of Revolution by Sean O’Mahony. Published by FDR Teoranta 1987 and was employed as a clerk on the managerial staff of the Nationality, Arthur Griffith's newspaper. MacMahon resumed his service with the Volunteers, becoming vice commandant of the 3rd Battalion.
South Longford by-election Griffith sent MacMahon and Joseph Curran to Longford to work for the imprisoned Joseph McGuinness' election on a Sinn Féin ticket in the South Longford by-election of May 1917. The election slogan developed was "Put him in to get him out!" and McGuinness was elected to Westminster. MacMahon commented: "We converted the hostile people who tried hard to beat us out of Newtownforbes."Military Archives File Reference SP11399 Joseph Michael Curran B Company 3rd Battalion 1916 for Pensions Collection.
In late 1917, after a 26-man Volunteer executive was established, it was decided to set up a headquarters staff. "Seven of the most prominent members of the resident executive met at the headquarters of the printers union at 35 Lower Gardener Street to select a chief of staff in March 1918. Those attending were Collins, Richard Mulcahy, Dick McKee, Gearóid O'Sullivan, Diarmuid O'Hegarty, Rory O'Connor and Seán MacMahon".Michael Collins The Man Who Won the War by T.Ryle Dwyer. Published by Mercier Press Cork. Revised edition 2009. (Page 84) In 1919 MacMahon became quartermaster-general of the IRA, as the Volunteers had now come to be known.Charles Townshend (2013). The Republic: The Fight for Irish Independence, 1918–1923 (London, Penguin), p. 233
Irish Republican Army MacMahon was the organiser of the famous Q Company based at Dublin Docks, which was finally organised into a unit in March 1921. John Kennedy was transferred from "B" Company, 3rd Battalion, Dublin Brigade, to his department to help run it. He also found time to organise the Volunteers at the various railway stations both in Dublin and throughout the country.
On another occasion, about this time, the British military carried out a raid on a business premises in Stephen's Green. Every room in the building with the exception of two were searched. One of these was the QMG's War Office.
Many meetings took place in Whelan's Pub at 49 Parnell Street. Owned and run by James Kirwan from Tipperary. He was a member of "D" Company 2nd Battalion, Dublin Brigade. Whenever there was an important meeting being held in the snug Richard Mulcahy would preside with MacMahon, Gearoid O Sullivan, Frank Thorton, Seán O’Connell, Michael Larken and of course Oscar Traynor these men were always present. Mick Collins was always in and out, keeping much of his funds hidden here. £3,000 at one time behind a brick in the wall of the cellar. Often used to buy arms. It was here that the escape from Kilmainham Gaol and of Sean Mac Eoin from Mountjoy were planned.Memories of James Kirwan as reported by Niall Carroll in a national newspaper.
Pax Whelan recalled a meeting of February 1921: "I was at a HQ meeting in a house on the quays. All the top people were there, Mick, Liam Mellows who was director of purchases, Cathal Brugha Minister for Defence, Rory O' Connor, Seán MacMahon Q.M.G., Liam Lynch and some others. They were discussing whether to bring in a boat with arms"Pax Ó Faoláin, p. 139.
He took part in several engagements during the Black and Tan war and was present during the night ambush when his Brother in Law, Leo Fitzgerald was killed in Great Brunswick Street on 14 March 1921.
Dublin awoke on the morning to 14 March 1921 to the news that six IRA mens, captured in an ambush at Drumcondra two months before, had been hanged.
The Labour movement called a half-day general strike in the city in protest at the hangings. The Republican government declared a day of national mourning. All public transport came to a halt.
By the evening, the streets cleared rapidly as the British-imposed curfew came into effect at 9pm each night. It was about 8 o’clock. The curfew was approaching. A company of Auxiliaries, based in Dublin Castle was sent to the area to investigate an explosion. It consisted of one Rolls-Royce armoured car and two tenders (trucks) holding about 16 men. Apparently the Auxiliaries had some inside information as they made straight for the local IRA headquarters at 144 Pearse Street. One later testified in court that – "I had been notified there were a certain number of gunmen there". Leo, with others, was protecting his brother in law and other senior staff attending a meeting. As soon as the Auxiliaries approached the building, fire was opened on them from three sides. Firing lasted for just five minutes but in that time seven people were killed or fatally wounded and at least six more wounded. Leo Fitzgerald was killed outright.
Treaty and Civil War
The Treaty was signed on 6 December 1921.
On the formation of the Regular Army in February 1922 he continued as Q.M.G.
When Michael Collins was shot in Béal na Blá and buried in Dublin, MacMahon help carry the coffin from St Vincents Hospital Dublin to the waiting gun carriage. Michael Collins brother gave him the handkerchief that was on Collins' person when he was shot.
In September 1922 he succeeded General Mulcahy as Chief of the General Staff. He was unknown not only to the Irish public but also to the British at Dublin Castle. At a reunion in Gormanstown in September 1922 General Mulcahy boasted of the great progress of the Army by indicating the newly appointed Chief of Staff as "the Army's first real Chief of Staff"