Seán Mac Eoin, Irish Republican Army (IRA) North Longford commander, is captured at Mullingar on March 1, 1921 and charged with the murder of a Royal Irish Constabulary (RIC) detective, dealing a severe blow to the IRA in that area.

Mac Eoin is born John Joseph McKeon on September 30, 1893 at Bunlahy, Granard, County Longford, the eldest son of Andrew McKeon and Catherine Treacy. After a national school education, he trains as a blacksmith at his father’s forge and, on his father’s death in February 1913, he takes over the running of the forge and the maintenance of the McKeon family. He moves to Kilinshley in the Ballinalee district of County Longford to set up a new forge.

Having joined the United Irish League in 1908, Mac Eoin’s Irish nationalist activities begin in earnest in 1913, when he joins the Clonbroney Company of the Irish Volunteers. Late that year he is sworn into the Irish Republican Brotherhood (IRB) and joins the Granard circle of the organization.

Mac Eoin comes to prominence in the Irish War of Independence as leader of an Irish Republican Army (IRA) flying column. In November 1920, he leads the Longford brigade in attacking Crown forces in Granard during one of the periodic government reprisals, forcing them to retreat to their barracks. On October 31, Inspector Philip St. John Howlett Kelleher of the RIC is shot dead in the Greville Arms Hotel in Granard. Members of the British Auxiliary Division set fire to parts of the town. The following day, Mac Eoin holds the village of Ballinalee situated on the Longford Road between Longford and Granard. They stand against superior British forces, forcing them to retreat and abandon their ammunition. In a separate attack on November 8, he leads his men against the RIC at Ballinalee. One constable is killed and two others are wounded.

On the afternoon of January 7, 1921, a joint RIC and British Army patrol consisting of ten policemen appears on Anne Martin’s street. According to Mac Eoin’s own testimony at his trial he is in the house in partial uniform, wearing Sam Browne belt and revolver with two Mills No. 4 bombs in his pocket. Owing to some females being in the house, he has to get out as to not endanger them. He steps out on the street and opens fire with his revolver. The leading file falls and the second file brings their rifles to the ready. He then throws a bomb, after which he sees that the entire force has cleared away, save the officer who was dead or dying on the street.

On February 2, 1921, the Longford IRA ambushes a force of the Auxiliaries on the road at Clonfin, using a mine it had planted. Two lorries are involved, the first blown up, and the second strafed by rapid rifle fire. Four auxiliaries and a driver are killed and eight wounded. The IRA volunteers capture 18 rifles, 20 revolvers and a Lewis gun. At the Clonfin Ambush, Mac Eoin orders his men to care for the wounded British, at the expense of captured weaponry, earning him both praise and criticism. He is admired by many within the IRA for leading practically the only effective column in the midlands.

Mac Eoin is captured at Mullingar railway station on March 1, 1921, imprisoned and sentenced to death for the murder of an RIC district inspector in the shooting at Anne Martin’s street in January 1921.

In June 1921, Henry Wilson, the British Chief of the General Staff (CIGS), is petitioned for clemency by Mac Eoin’s mother, his brother Jemmy, and the local Church of Ireland vicar, but passes on the appeals out of respect for the latter two individuals. Three auxiliaries had already given character references on his behalf after he had treated them chivalrously at the Clonfin Ambush in February 1921. However, Nevil Macready, British Commander-in-Chief, Ireland, confirms the death sentence describing Mac Eoin as “nothing more than a murderer.”

While imprisoned Mac Eoin is elected to Dáil Éireann at the 1921 Irish general election, as a TD for Longford–Westmeath. He is eventually released from prison, along with all other members of the Dáil, after Michael Collins threatens to break off treaty negotiations with the British government unless they are freed.

Mac Eoin joins the National Army and is appointed GOC Western Command in June 1922. His military career soars after the Irish Civil War. He is appointed GOC Curragh Training Camp in August 1925, Quartermaster General in March 1927, and Chief of Staff in February 1929.

Mac Eoin resigns from the Army in 1929, and is elected at a by-election to Dáil Éireann for the Leitrim–Sligo constituency, representing Cumann na nGaedheal. At the 1932 Irish general election, he returns to the constituency of Longford–Westmeath, and continues to serve the Longford area as TD until he is defeated at the 1965 Irish general election.

During a long political career Mac Eoin serves as Minister for Justice (February 1948 – March 1951) and Minister for Defence (March–June 1951) in the First Inter-Party Government, and again as Minister for Defence (June 1954 – March 1957) in the Second Inter-Party Government. He unsuccessfully stands twice as candidate for the office of President of Ireland, against Seán T. O’Kelly in 1945 and Éamon de Valera in 1959.

Mac Eoin retires from public life after the 1965 general election and dies in Dublin on July 7, 1973.