Former head of IRA who saw himself as successor to Wolfe Tone

Ruairí Ó Brádaigh, who has died aged 80, was a former president of Republican Sinn Féin, having previously held the presidency of Provisional Sinn Féin. He also headed the IRA.

Twice at the centre of bitter splits in the republican movement, he was driven by a fundamentalist commitment to the tenets of incendiary nationalism. He defined a republican as “one who rejects the Partition Statelets in Ireland and gives his allegiance to and seeks to restore the 32-County Republic of Easter Week”.

Insisting that Irish republicanism owed nothing to revolutionary movements elsewhere, he once told the academic Fred Halliday: “We have no need of your Che Guevaras and your Ho Chi Minhs. We have Robert Emmett, O’Donovan Rossa, Cathal Brugha, Dan Breen.”

Born Peter Roger Casement Brady in Longford in 1932, he was the son of Matt Brady and his wife May (née Caffrey). His father, a War of Independence veteran, was a non-party member of Longford County Council, while his mother was a local government official.

He studied at University College Dublin, graduating with a commerce degree in 1953, and became a vocational schoolteacher. He attended his first Sinn Féin árdfheis in 1951, three years after the then moribund organisation had been taken over by the IRA. Active in the 1950s Border campaign, he was imprisoned several times. He was in 1957 one of four Sinn Féin candidates elected to the Dáil on an abstentionist ticket.

Chief-of-staff of the IRA in the early 1960s, it was he who formally ended the Border campaign and ordered IRA units to dump arms. As the IRA regrouped in the 1960s he opposed the shift to the left and adoption of electoral politics promoted by Cathal Goulding.

The outbreak of civil disorder in Northern Ireland, which caught the IRA unawares, drove Ó Brádaigh and other likeminded republicans to assert the primacy of the gun over the ballot box.

In December 1969 the IRA split and the Provisional army council was established. When most delegates at the Sinn Féin árdfheis in January 1970 voted to drop the policy of abstentionism Ó Brádaigh was among those who walked out. Other reasons he gave for the walk-out were the abandonment of Northern nationalists and the “extreme form of socialism being pushed on the movement”. Provisional Sinn Féin was founded the same day and he was elected president; he was also made a member of the army council.

Political violence escalated sharply in the years that followed as the Provisionals waged war on the Northern Ireland state. Ó Brádaigh, along with his close associate Daithí Ó Conaill, was to provide the core of Provisional ideology and strategy until the late 1970s. He was the author of the Éire Nua policy, which the IRA adopted in the early 1970s. It envisaged four provincial parliaments within a federal framework and was designed to assuage unionist fears of a united Ireland with the promise of a majority in Dáil Uladh.

He took part in the Feakle talks with Protestant clergymen and represented the IRA at meetings with senior British officials that ensued.

In the course of the discussions, held during the IRA ceasefire in 1975, Provisional leaders were led to believe that the British government was seeking “structures of disengagement”. When it became clear that the British had no intention of withdrawing, Northern republicans complained that the army council had been fooled into taking part in meaningless talks and tricked into calling a ceasefire that left the IRA weakened and demoralised. Ó Brádaigh was singled out for particular blame.

Differences over electoral strategy had already emerged, and his proposals for participation in local and Assembly elections in Northern Ireland, albeit on an abstentionist basis, were rejected. Likewise his plan that Sinn Féin should contest the European elections in 1979 was rejected.

By now moves to ditch Éire Nua were afoot. Dropped by the IRA in 1979, the policy was diluted almost beyond recognition by Sinn Féin the same year. In an angry behind-the-scenes confrontation with Gerry Adams at the 1982 árdfheis, Ó Brádaigh refused to disown it, but his plea to delegates not to "swap a policy for a slogan" failed to carry the day.

He suffered a further setback in 1982 when Christin ni Elias, a close ally on the árd comhairle, was expelled from Sinn Féin at the behest of the IRA. He stood down as leader in 1983, citing lack of support for his policies, and was succeeded by Adams. Following the decision at the 1986 árdfheis to drop abstentionism, Ó Brádaigh and others left to form Republican Sinn Féin (RSF), which gave its support to the Continuity IRA (CIRA) army council.

In 1997, in the aftermath of a CIRA bomb blast in Markethill, Co Armagh, he denied that the organisation was the military wing of RSF. Asked in 2005 if he was a member of the CIRA army council, he replied: “I won’t answer that question.”

He stood down as RSF president in 2009.

Lionised by the faithful few, but derided by many erstwhile comrades, he never deviated from the beliefs that inspired him as a young man to embrace republicanism. He saw himself “in a line of succession going back beyond Wolfe Tone to the Gaelic leaders of resistance to the Norman invasion”. It was not he but those who had endorsed partition that were in the wrong.

His wife, Patsy O’Connor, four sons and two daughters survive him.