Ian Paisley, a Protestant minister and political agitator in Northern Ireland whose incendiary rhetoric stoked anti-Catholic violence for decades and who made a stunning late-career reversal that thrust him to a power sharing leadership role, died Sept. 12 in Belfast. He was 88.

The death was announced by his wife. He had a history of heart ailments.

Paisley became Northern Ireland’s co-leader in 2007 after entering an agreement with Sinn Fein, the Catholic-led political arm of the outlawed militant Irish Republican Army.

It was an unlikely alliance between two parties who, for more than three decades of Northern Irish history, were sworn enemies. That the partnership prevailed was largely owed to Paisley, said former U.S. Sen. George J. Mitchell, D-Maine, who served as the U.S. envoy to Northern Ireland in the 1990s.

“I think he deserves credit for making possible the changes that have taken place in Northern Ireland,” Mitchell said. “He did it through the force of his personality and his intellect.”

Paisley began his career in the 1950s as an evangelist minister with a fringe congregation of a few dozen. Through his charisma and political acumen, he became Northern Ireland’s most powerful politician and leader of its largest party, the Democratic Unionist Party, which he helped establish in 1971.

Representing Northern Ireland, he served in Britain’s House of Commons for three decades starting in 1970 and was elected to the European Parliament in 1979 with a record number of votes.

At 6-foot-4 and 240 pounds, Paisley’s hulk and predilection for vitriol made him an intimidating presence in Northern Ireland’s political landscape. Whether from the pulpit or parliament, he was an expert at sparking controversy. In Northern Ireland’s bloody history, few figures were considered as divisive as Paisley.

He rose to prominence in the 1960s at the start of “the Troubles,” in which Ireland was engulfed in sectarian violence between Catholics and Protestants. The bloodshed lasted more than 30 years.

As a staunch unionist, Paisley fought to keep Northern Ireland in the United Kingdom and spoke vehemently against any proposals to integrate the country with its southern neighbor, the Republic of Ireland, a sovereign body composed of a Catholic majority.

For decades, Paisley had rejected any form of political compromise with Northern Ireland’s Catholic minority and responded to calls for negotiations with his signature war cry: “No surrender!”

A self-proclaimed bigot, he once interrupted a speech by Pope John Paul II by calling the pontiff the antichrist. He said he considered all Catholics to be members of the Irish Republican Army, which he branded as a collective of terrorists.

Although he preached against the use of force in his church, his acidic words carried weight. On several occasions, his sermons caused riots. Paisley was said to be the target of multiple assassination attempts, and a sniper’s bullet once penetrated his car and missed him by inches.

Ian Richard Kyle Paisley was born April 6, 1926, in Armagh, Northern Ireland, the son of a Baptist minister. After high school, he worked as a farmer before entering the Protestant ministry. He was ordained in 1946.

Five years later, he splintered from the official Protestant ministry and formed his own congregation, the Free Presbyterian Church of Ulster. Initially, his followers numbered barely more than a dozen. Yet his sermons, laden with salvos against the pope and the Catholic Church, quickly earned him mainstream recognition during a period of heightened sectarian tensions.

In response to his firebrand oratory, Northern Ireland’s official Presbyterian Church publicly disassociated itself from him. An astute handler of public affairs, he was able to turn his notoriety into power by packing his church’s pews to capacity. As his popularity grew, his sermon topics turned to matters of the state.

In 1963, he organized a march on the Belfast city hall to assail the government’s lowering of the flag after the death of Pope John XXIII. Later, he was jailed twice for unlawful assembly after marches he led turned into riots. Police regularly employed tear gas to disrupt his gatherings.

As the Troubles worsened, the streets of Belfast and beyond echoed with the explosions of car bombs and the cracks of gunshots. Paisley’s rabble-rousing antics and talent for demagoguery led him to be known as “the clergyman in jackboots.”

He was also known as “Dr. No,” for his obstinacy and an honorary doctorate he received in 1966 from South Carolina’s fundamentalist Bob Jones University. He continued to publish books with exclamatory titles such as “United Ireland — Never!” (1972) and “No Pope Here!” (1982).

In the 1990s, Paisley refused to participate in a U.S. effort led by the envoy Mitchell to craft a peace accord between the Catholics and Protestants of Northern Ireland. The agreement was meant to create a power-sharing executive position, foster positive relations between the two factions, and called for a disarmament of militant groups, mainly the IRA.

Paisley said he would not be party to any negotiations involving Sinn Fein. The document was completed without Paisley’s input and was later known as the Good Friday agreement, for the date in April 1998 it was signed.

For their work leading the talks that led to the Good Friday Agreement’s ratification, two moderate Northern Irish politicians, David Trimble of the Protestant Ulster Unionist Party and John Hume of the Catholic Social Democratic and Labor Party, received the 1998 Nobel Peace Prize.

But the award, and the peace agreement’s slow path to success, cost them politically. In 2003 elections, both their parties lost majority status in the Northern Irish assembly.

The reversal of fortunes led Paisley’s party, the DUP, to become the biggest in the country. Sinn Fein also benefited by winning new seats in the Assembly to become the second-biggest party.

Mitchell said Paisley’s newfound power made him “instrumental in moving the peace process forward.”

“I think he became convinced that the last few years were better for the people he represented than a return to the conflicts of the past,” Mitchell said. “He made possible the full implementation of the full agreement. It couldn’t have happened without his involvement and leadership.”

By the early 2000s, the IRA began to put down its arms. The sectarian strife had killed an estimated 3,500 people.

The thaw in relations between Catholics and Protestants allowed Paisley to agree in 2007 to form an alliance with Sinn Fein, which was led by former IRA commando Martin McGuinness. The unlikely pair shared equal power of the country’s domestic affairs, with Paisley as first minister and McGuinness as deputy first minister.

“After a period of tough negotiations, it was my view that, provided our conditions were met, the overwhelming majority of the people of Northern Ireland wanted me to do the deal,” Paisley once said. “It was as simple as that.”

He stepped down as first minister in 2008 and began to retire from public life amid health problems. In 2010, he left the British House of Commons; his son, Ian Paisley Jr., won his seat.

Survivors include his wife, the former Eileen Cassells; five children; many grandchildren and great-grandchildren.

“Ian Paisley’s contribution to peace, after all the years of division and difference, was decisive and determinative,” former British prime minister Tony Blair said in 2008. “The man famous for saying ‘no’ will go down in history for saying ‘yes.’”