MacDonagh, Joseph (1883–1922), politician and businessman, was born 18 May 1883 in Cloughjordan, Co. Tipperary, youngest of six surviving children (four sons and two daughters) of Joseph MacDonagh (1834–94), native of Rooskey, Co. Roscommon, and Mary MacDonagh (née Parker; d. 1908), a Dublin native, both of whom were national school teachers. He was educated in his father's school in Cloughjordan, and at Rockwell College, Cashel, Co. Tipperary. Prior to the execution of his eldest brother, Thomas MacDonagh (qv), one of the signatories of the Easter 1916 proclamation of the republic, he seems to have had no involvement in politics, but worked as a customs-and-excise officer with Inland Revenue in Thurles, Co. Tipperary. Interned after the rising owing entirely to his kinship with one of the insurgent leaders, he was also compelled to retire from the civil service. Moving to Dublin by September 1916, he was headmaster for a time (probably 1916–17) of St Enda's school (the bilingual school where Thomas had formerly served on the staff under Patrick Pearse (qv)), which had reopened after the rising in Cullenswood House, Oakley Road, Rathmines. By 1918 he was in private practice as an income tax recovery expert; he later quipped that by recovering thousands of pounds annually for clients, he had done greater harm to the British government than any other Irishman. He was also partner by 1919 in an insurance brokerage with fellow Sinn Féin TD William Cosgrave (qv); after Cosgrave's departure, the firm traded from 1920 as MacDonagh & Boland, with offices first on Dame St., and latterly on College Green.
MacDonagh's prominence in the post-1916 reorganisation of Sinn Féin commenced at the convention of advanced nationalists (19 April 1917) summoned by Count George Noble Plunkett (qv) after his parliamentary by-election victory. MacDonagh made a resounding speech ratifying Plunkett's determination not only to abstain from attendance at Westminster, but also to affirm the principles of the republican Easter Week proclamation rather than the dual-monarchy programme of Sinn Féin under Arthur Griffith (qv). After campaigning vigorously on behalf of the successful by-election candidacy of Éamon de Valera (qv) in Clare East, he was arrested (30 August) and sentenced to six-months’ imprisonment for making a seditious speech. He joined in the hunger strike of republican prisoners seeking prisoner-of-war status in Mountjoy jail, on which Thomas Ashe (qv) died after enduring forcible feeding (25 September); released with the other surviving strikers, he was a principal witness at the emotional inquest into the circumstances of Ashe's death. Elected to the Sinn Féin executive at the October 1917 ard-fheis, at which the party adopted a republican constitution, he was alternately rearrested and released on several occasions under the ‘cat-and-mouse act’, enduring further hunger strikes in both Belfast and Dundalk jails, before serving out in its entirety the original six-month sentence (1917–18). After deportation to England and while incarcerated in Reading jail, he was returned unopposed in the December 1918 general election as Sinn Féin candidate in Tipperary North (1918–21), and was released in time to attend the second session of the first Dáil Éireann (10 April 1919). With the dáil driven underground after its proscription (September 1919), MacDonagh protested against the infrequency of sessions, querying whether ‘private members [were] to abstain from Dublin as well as Westminster’ (Mitchell, 57).
Elected in January 1920 to both Dublin corporation (alderman for Merchants’ Quay ward (1920–22)) and Rathmines town council (where he exercised his trenchancy in debate as Sinn Féin leader on a body evenly divided with unionists), he concentrated his political energies on local government until appointment in January 1921 as acting dáil minister for labour, and director of the Belfast boycott. Exercising effective authority over the labour department because of the imprisonment of the minister, Constance Markievicz (qv), he sought to define a comprehensive industrial and economic strategy, and established a labour commission to formulate proposals. The resultant radical plan for supplanting capitalist ownership by developing cooperative and distributive industrial structures was ignored by his cabinet colleagues. MacDonagh's organisation and enforcement of the Belfast boycott – a response to the anti-catholic rioting of July 1920, and expulsion of workers from jobs and families from homes – was relentless and efficient: he appointed a team of boycott organisers and local boycott committees empowered to impose fines and to seize goods, and blacklisted firms that were facilitating circumvention of the boycott by trans-shipment of Belfast goods through non-boycotted northern towns or through British ports.
Throughout the war of independence he was constantly on the run, usually under disguise as a priest, and was imprisoned for a time in Mountjoy in 1920. One of four Sinn Féin candidates returned unopposed to the second dáil for Tipperary Mid, North, and South (1921–2), after a cabinet reorganisation (August 1921) following the truce he remained as boycott director but was removed from the labour department. Bitterly opposed to the Anglo–Irish treaty, in the dáil debates he responded to Griffith's assertion that the agreement was indeed a treaty concluded between two sovereign nations by asking why the pro-treatyites were conducting the sovereign Irish nation into the British empire, and whether they were doing so ‘with their heads up or their hands up’ (Treaty deb., 75). Manager of the anti-treaty bulletin Poblacht na h-Éireann, in the June 1922 election he was returned on the first count to the third seat in his constituency. Arrested soon after the outbreak of the civil war, he escaped from Portobello military barracks. Rearrested on 30 September and imprisoned in Mountjoy jail, he fell seriously ill with acute appendicitis, but refused to sign the required form to secure release for medical treatment because it implicitly recognised the legitimacy of the Free State government. Transferred at length to the Mater Misericordiae private nursing home, he underwent an operation, but two days later, having developed peritonitis, he died 25 December 1922. He was buried in Glasnevin cemetery.
A small, supple man with alert blue eyes, MacDonagh wielded a swift and stinging tongue in debate. It was said that he indulged his caustic wit more for the delight in the bon mot than for the bitterness of the invective. Genial in company, with a store of amusing anecdote, he was celebrated for hearty humour even in the face of hardship and danger; on a prison sickbed days before his death he referred to another inmate, bald-headed like himself, ‘who wears his hair like mine’ (O'Malley, 204). He married (1913) Margaret (‘May’) O'Toole of Dublin; they had one daughter and two sons. They resided in Rathmines, first at 86 Moyne Road, before moving during 1922 to 9 Palmerston Road.