Ó’Brádaigh was active in the Border campaign and arrested for such activity. He headed the assault party on Arborfield on 13 August 1955 and was elected to the IRA Executive. He was arrested for his part in the attack of Derrylin Barracks on 30/31 December 1957 and sent to the Curragh, from which he escaped on 24 September 1958 along with Daithi O’Conaill. At the Army Convention in May of 1959, Ó’Brádaigh was voted Adjutant General under Sean Cronin. Six months later he was arrested in Roscommon town after attending a church service for the local school’s headmaster. Because he didn’t answer questions posed by the Gardaí, he was sentenced to six months in Mountjoy. Released on 26 May 1960, he returned to Longford amid public fanfare.
Ó’Brádaigh turned over the Chief of Staff position to Cathal Goulding on 7 September 1962 and returned to Roscommon town, where he taught in the local vocational school. In December of 1964, he was elected chairperson of the Roscommon Sinn Féin. In February 1966 he was selected as a Sinn Féin candidate for Fermanagh/Tyrone in the Westminster elections. But the shadow of “illegal activity” followed him. On 31 May 1972 as President of Sinn Féin, he was arrested and again sent to the Curragh, from which he was released a year later.
After leaving the military wing of the IRA, Ó’Brádaigh remained at the forefront of Irish politics. He was elected as president of Sinn Féin—a position he held until Gerry Adams succeeded him in 1983. A year later he and his wife, Patsy, and two of their children were involved in a car wreck that resulted in injuries which took months to heal. That same year he was elected Secretary of Roscommon Comhairle Ceantair and attended the Árd Fhéis as a delegate.
Totally committed to the legacy of a Republic and the eminence of the Second Dáil, the cornerstones of the Sinn Fein policy stood for armed struggle to achieve the Republic and rejection and avoidance of Leinster House as a corruption of the Republican ideals.
Ó’Brádaigh was, however, part of the negotiating team that achieved a truce and continued negotiations with the British in 1975. While the Irish were talking with the Crown representatives about withdrawal from Northern Ireland, the English were building H-Block (detention center in the north) and systematically handing over “peace keeping” duties to the enlarged RUC. The ceasefire broke down.
The year 1986 signaled a change in tempo. Younger members of the organisation reasoned that loaded guns were appropriate weapons to be aimed northward, but capture of the southern government was going to have to be attempted by a different strategy. Note from Ó’Brádaigh’s own pen: “Since the end of the Irish Civil War in 1923, no one—Republican or other—had attempted to overturn the Dublin parliament or Leinster House by force. This is historical fact. But why accept the established though partitionist and collaborationist twenty-six county parliament?” (Private correspondence October 22, 1996.)
How then was Sinn Féin going to overtake the Dublin government and refocus its legislation? The answer goes back to the original idea of Sinn Féin―to succeed in electing candidates who would exhibit their contempt for the British Parliament by not taking a seat in its chambers; however, the resolution passed at the 1986 convention of Sinn Féin specifically directed its members to challenge delegates at the voting polls and to take their seats in the twenty-six county Dáil thus challenging its policies.
Like De Valera in the late 1920s, the younger leadership of Sinn Féin felt isolated and unable to affect change while sitting on the sidelines watching the game being played out. Rather than trying to construct an All Ireland parliament with new perimeters and new rules, the younger members chose to become players in the Dublin Dáil. They felt that to be a part of the tournament, they had to get off the bench and onto the court.
Ó’Brádaigh, who always treasured the abstentionist policy, could not swallow this unpalatable pill of parliamentary politics. He and his comrades objected to this strategy by pointing out that all who have formerly accepted the twenty-six county state have ended up abandoning the freedom fight in the North and helping the British rule it. They feared the young turks (the Provisional IRA) would be soaked up in this same morass. Thus he, along with other prominent Republicans, splintered off from the Provisional IRA and started a new party, Republican Sinn Féin. He was President of that organisation until he resigned due to age and ill health in October 2009. After a battle with cancer, he died 5 June 2013.