DUBLIN — Seamus Mallon, a dogged champion of nonviolent struggle and one of the key architects of peace in Northern Ireland, died on Friday at his home in Markethill, County Armagh. He was 83.
His death was confirmed by his family, who said he had been suffering from cancer.
As a leading member of the Social Democratic and Labour Party, which promotes Irish unity through nonviolent means, Mr. Mallon spent his life campaigning for an end to killings and abuses by all sides in the conflict in Northern Ireland known as the Troubles — including the republican gunmen from his own Roman Catholic community, who were fighting to unite north and south, and the British forces and Protestant loyalist gangs that sought to defend the union with Britain. At least 3,500 people died in 30 years of bombings and shootings.
The leader of his party, John Hume, shared the Nobel Peace Prize with the unionist leader David Trimble for their parts in the Good Friday Agreement of 1998, which ended the conflict. But it was Mr. Mallon, a stickler for both principle and detail, who worked out the nuts and bolts of the party’s position, and who held the party together during tense and drawn-out talks.
He then became the party’s leader, and Mr. Trimble’s deputy first minister, in the first power-sharing administration set up under the deal. He endured three years of often prickly collaboration with Mr. Trimble before resigning to care for his ailing wife, Gertrude.
As deputy first minister, Mr. Mallon was particularly proud of having insisted, despite strong unionist opposition, that the Royal Ulster Constabulary, which had become dominated by Protestants, be reformed and replaced by the new Police Service of Northern Ireland, with broader cross-community membership and support.
Active until the end, he published a memoir, “A Shared Home Place,” last year. In it, he restated his principles of cooperation, human contact and mutual respect.
At a time when Ulster’s mainly Protestant unionist community, once the majority in Northern Ireland, seems likely to become a minority, and talk of a united Ireland has been revived, Mr. Mallon broke with many traditional nationalists to say that a simple majority vote should not be enough to reunite the island.
Instead, he argued in his book, a supermajority of at least 60 percent, including the support of at least 40 percent of unionists, should be required for a unity vote. Otherwise, he argued, Ulster Protestants might become a disaffected and potentially violent minority in a united Ireland, just as Roman Catholics had been in Northern Ireland
Few politicians in Northern Ireland could have had a more intimate experience of the Troubles than Seamus Frederick Mallon.
Born on Aug. 17, 1936, the son of Frank Mallon, the principal of a small Roman Catholic elementary school, and Jane (O’Flaherty) Mallon, a homemaker, he lived all his life in Markethill, a mainly Protestant and loyalist village that was itself an enclave in the strongly Catholic border region of South Armagh, later the scene of some of the worst of the killing.
As a child, he watched neighbors march under his window in the annual Orange Order parades celebrating Protestant domination of his own people. He later said he had enjoyed the spectacle, and the lively marching bands.
His ability to see the humanity in those across the sectarian divide from him was the leitmotif of his career in politics. In the bleak 1970s, when Protestant murder gangs were targeting innocent Catholics, including several of his friends, and Irish Republican Army gunmen stalked police reservists and part-time soldiers he’d known all his life, Mr. Mallon made a point of attending the funerals of all of the victims in his area — Catholic or Protestant, nationalist or unionist.
In his memoir, he recalled walking after the funeral cortege of one of 10 Protestant workmen murdered by the I.R.A. in the Kingsmill Massacre of 1976:
“The constant drizzle and a dank, gray mist added to the pall of grief that seemed to envelop the silent, heartbroken village. I felt desperately alone as a nationalist politician among those grieving unionists: I could hear my own footsteps.”
On another occasion, a neighbor of his, who was a police reservist, escorted him to safety from another Protestant funeral, where he’d been told he wasn’t welcome. Three weeks later, he came upon the same young police officer, dying from republican gunshots in the street in Markethill.
“Seamie, tell them all I love them,” the dying man, cradled in Mr. Mallon’s arms, told him.
Himself under threat from both loyalist murder gangs and republican terrorists, who regarded the nonviolent Social Democratic and Labour Party as sellouts or traitors, Mr. Mallon drove the notoriously ambush-friendly back roads and hedgerows of South Armagh with no protection. He refused an offer of a police bodyguard: The officers sent to look after him, he pointed out, would only be targets themselves.
Having attended the same small elementary school where his father was principal, young Seamus went first to St. Patrick’s College in Armagh and afterward to the Abbey Christian Brothers’ School in Newry, where he was a member of the first Gaelic football team to win the highly prestigious provincial schools championship.
After school, he followed his father into elementary-school teaching, studying at St. Joseph’s Teacher Training College in Andersonstown, Belfast. He would have preferred to study law, but such avenues were closed to him at the time.
“If you were Catholic and didn’t have money,” he later recalled, “you went into teaching, the priesthood or, if you could get in, the civil service.”
Teaching at his old high school in Newry, he gradually became drawn into politics in the 1960s as an activist in the Northern Ireland civil rights movement, which, emulating the black struggle in the United States, sought to end widespread discrimination against the Catholic minority in housing, policing, welfare and jobs. This eventually led him to join the Social Democratic and Labour Party, for which he became a local councilor and a member of Northern Ireland’s short-lived assembly of the early 1970s.
He later served briefly as a member of the Senate in the Irish Republic and then, from 1986 to 2005, as a member of the British Parliament for Newry and Armagh. After the Good Friday Agreement of 1998 he was also elected to the new power-sharing assembly at Stormont, near Belfast.
In 1964 he married Gertrude Cush, a nurse. She died in 2016. He is survived by their daughter, Orla Mallon; three sisters, Maura Mallon, Jean Povey and Kate Leamy; and a granddaughter.
Among the many tributes paid to Mr. Mallon was one from Bill Clinton, who was president when the Good Friday Agreement was signed and played an active role in the talks.
“Seamus never wavered from his vision for a shared future where neighbors of all faiths could live in dignity,” he said, “or from the belief he shared with John Hume and the entire S.D.L.P. that nonviolence was the only way to reach that goal.”
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