O'Brien, Nora Connolly (1893–1981), republican and socialist activist, was born at 6 Lothian St., Edinburgh, Scotland, second among six daughters and one son of James Connolly (qv), of Edinburgh, the socialist republican leader (at the time, labourer, journalist, and secretary of the Scottish Socialist Federation), and Lillie Connolly (née Reynolds), originally of Carnew, Co. Wicklow. Her father's career took the family to Dublin (1896–1904), Troy, New York (1904–5), and Newark, New Jersey (1905–10). Attending primary schools in each of these locations, she was ‘a bright, imaginative child who astonished her teachers by her forwardness’ (Greaves, 147). The attention paid by James Connolly to Nora's intellectual and political development is evidence of the sincerity of his feminist convictions. From an early age she attended her father's political meetings, accompanying him on a four-month Scottish lecture tour at age 8 (1902). The tragic death of her older sister in a domestic accident on the eve of embarkation to America (August 1904) left Nora as the eldest child. Against her father's wishes, she ceased formal education at age 13 (1907) and worked in a millinery store to contribute to the family finances. She assisted in the New York office of his Irish Socialist Federation and by 1910 was New York business agent of the Federation's organ, The Harp. The family returned to Dublin (December 1910), then settled in Belfast (1911), where Nora worked in a garment wareroom and immersed herself in the labour and republican movements. She joined Na Fianna Éireann's Belfast branch, the first to admit girls ‘because they refused to be excluded’ (Ward, 104); helped organise a Young Republican Party that agitated against the prospect of partition as the home rule crisis intensified; and collected support funds for the locked-out Dublin workers (1913–14). After the Howth gun-running (26 July 1914), she smuggled rifles and ammunition to the Irish Volunteers' Belfast contingent. The nature of the secret message she conveyed from her father to Irish republicans in New York (December 1914) remains speculative: possibly notification of the Irish Republican Brotherhood's decision for a rising during the great war; possibly information on Belfast ship-building activity for relay to German agents. She was principal organiser (1915) of Cumann na mBan's Belfast branch, exceptional for undertaking (largely under her influence and that of her sister Ina) similar roles to those of the all-male Volunteers, including rifle practice and drill.
In early April 1916 she was dispatched by the IRB military council to accompany Liam Mellows (qv), recently deported to England, on his clandestine return (disguised as a priest) to Ireland to command the Galway Volunteers in the impending Easter rising. On 22 April she led the Cumann na mBan first aid corps that accompanied the Belfast Volunteers to the Northern Division's mobilisation in Co. Tyrone. On receipt of the countermanding order from Eoin MacNeill (qv), she travelled by night train to Dublin to obtain clarification from her father. On Easter Monday morning (24 April) she returned to Tyrone bearing a counter-order from Patrick Pearse (qv). After fruitless efforts to remuster the Northern Division, she and her sister Ina returned to Dublin, walking most of the distance from Dundalk owing to rail disruptions, passing a night in a field near Balbriggan, and arriving in the capital hours after the insurgents' surrender. She accompanied her mother on a final visit to her wounded father imprisoned in Dublin castle, hours before his execution (12 May). A subsequent third-person memoir, Portrait of a rebel father (1935), recounts these early years.
With the family virtually penniless, Connolly, in accord with her father's expressed wish, evaded post-rising travel restrictions and went to America (August 1916) to seek work, but soon was propagandising for the republican cause. Lionised by Irish-American organisations as the first Easter-week participant to visit the country, she addressed large audiences throughout the eastern states (1916–17). The unbroken tradition (1918), an anecdotal account of her role in the prelude to and progress of the rising, was banned in the USA as prejudicial to the wartime alliance with Britain. Excluded by the Home Office from return to Ireland, Connolly entered incognito from England (summer 1917) and lived in hiding for a time. Disagreeing with Labour party neutrality on the national question, she canvassed for Sinn Féin in the December 1918 general election and remained active in Cumann na mBan throughout the 1919–21 troubles. During the truce (September 1921) she was part of a left-wing group that assumed control of the tiny Socialist Party of Ireland, expelled the moderate leadership, and reconstituted (October 1921) as the Communist Party of Ireland (dissolved 1923); she served as party treasurer under her brother, Roddy Connolly (qv), as president. After marriage (February 1922) to Seamus O'Brien, commercial traveller and war-of-independence courier for Michael Collins (qv), she adopted the surname Connolly O'Brien. During the first weeks of the civil war (June–July 1922) she supervised an anti-treaty first-aid post at Tara Hall, Dublin. She was secretary to the republican minister of finance, Austin Stack (qv), until her arrest in November 1922. Incarcerated in Mountjoy, Kilmainham, and North Dublin Union (both she and her husband were in prison on their first wedding anniversary), she was released (August 1923) on a writ of habeas corpus on grounds that her arrest had been unlawful. She co-founded with her brother and others the short-lived Workers' Party of Ireland (1926–7), but resigned with most other party officers after failing to supplant the Irish Worker League of James Larkin (qv) as the Irish affiliate of the Communist International. In 1934 she organised with Peadar O'Donnell (qv) the Belfast branches of Republican Congress, enlisting sizeable numbers of Shankill and Newtonards protestant workers into James Connolly Workers' Republican Clubs. At the organisation's Rathmines congress (29–30 September) she supported the resolution calling for a new radical political party to pursue a workers' republic; when defeated by O'Donnell's contrary resolution for a worker-led republican united front, she and her group withdrew from the congress. She operated the Labour Party's Drimnagh, Dublin, branch, but resigned from the party when the workers'-republic objective was deleted from its constitution (1939). During the 1930s she worked firstly as business correspondent, secondly as statistician, in the Irish Transport and General Workers' Union. During the second world war she was a telephone/telegram agent (GPO, Dublin) until ill-health forced her retirement. An independent member of Seanad Éireann (1957–69) as nominee of taoisigh Éamon de Valera (qv) and Seán Lemass (qv), she opposed several Fianna Fáil proposals, notably the 1959 effort to abolish proportional representation, and a church-promoted bill to consign female juvenile offenders to Magdalen asylums. Despite failing eyesight, she coedited the polemical selection James Connolly wrote for today (1978) and dictated a final memoir and polemic, We shall rise again (1981), in which, against the background of the H-block hunger strikes, she expressed qualified support for the ‘armed struggle’ policies of Provisional IRA.
Connolly O'Brien's husband, Seamus O'Brien (d. 1962), worked from c.1940 in the Department of Defence; they had no children. She died in Dublin on 17 June 1981. Each of her three published memoirs contains ample autobiographical material.