Garret FitzGerald; former prime minister of Ireland

Flags were lowered to half staff as politicians of all parties paid tribute to Mr. FitzGerald as a man of integrity and vision.

Queen Elizabeth II of Britain, on the third day of her visit to Ireland, hailed Mr. FitzGerald as “a true statesman’’ who had “made a lasting contribution to peace.’’

Mr. FitzGerald — former leader of Fine Gael, Ireland’s perennial number two party — lived just long enough to see Fine Gael finally overtake its old enemy, Fianna Fail, to claim first place in a national election this year for the first time.

His closest political colleagues said he was deeply heartened to see this week’s first-ever trip to Dublin by the queen, a crowning event of the Northern Ireland peace process that Mr. FitzGerald did much to promote during his two terms in office between 1981 and 1987.

“Garret was always burning with this desire for peace and reconciliation,’’ said Gemma Hussey, a former government colleague. “In a way, as he was slipping off, this was a wonderful week for him to go.’’

Mr. FitzGerald’s greatest triumph was the Anglo-Irish Treaty of 1985 with Britain, an achievement shaped by his Dublin upbringing with a northern Protestant mother and southern Catholic father.

After suffering years of rebuffs, in 1985 he persuaded Margaret Thatcher, then Britain’s prime minister and renowned for her coolness to Irish nationalism, that she must concede a role for the Republic of Ireland in managing the north’s affairs for the first time.

The treaty infuriated the British territory’s Protestant majority, but proved to be a game-changer for peace. It created a space where Ireland and the north’s Catholic leaders could begin to engage with both Britain and the north’s Protestants, culminating in the Good Friday peace accord of 1998.

“Garret cared deeply about peace on our island,’’ said Bertie Ahern, who as Ireland’s prime minister engaged with Tony Blair, his British counterpart, and Northern Ireland party leaders in negotiating the Good Friday agreement.

“He was generous in his advice and vocal in his encouragement of my efforts to secure what became the Good Friday Agreement and then to get it implemented,’’ Ahern said.

Mr. FitzGerald was a unique figure in Irish politics: an intellectual and university economist who turned to Parliament in midcareer.

His polished manners and soft-spoken wit offered a polar opposite to Ireland’s dominant politician of the day, the corrupt and coarse Charles Haughey. Their parliamentary battles were the centerpiece of Irish political life in the 1980s.

While Haughey embraced a millionaire’s lifestyle funded by secret donations from businessmen, Mr. FitzGerald was credited even by his most ardent opponents with an innate honesty and humility, although critics said he lacked the cutthroat judgment and cunning needed to succeed in Irish politics.

“I greatly admired his integrity, his abilities, and his unfailing politeness and courtesy,’’ said the current Fianna Fail leader, Micheál Martin. “He was a person who cared deeply about Ireland.’’

He was smarter than just about anyone else in the room, too.

“He was miles ahead of most people in most conversations,’’ said Hussey, who recalled how Mr. FitzGerald amused himself by studying troves of decades-old statistics. One of his greatest joys, she said, was to meet a fellow statistician.

“Sometimes he went down side alleys in discussions, and they could go on for hours,’’ said Prime Minister Enda Kenny, who was a Fine Gael backbencher when Mr. FitzGerald was in power. “He had an eternal optimism over what could be achieved through politics.’’

Mr. FitzGerald, a relative liberal in his conservative Catholic party, sought greater roles for women in public life. He was an enthusiast for the European Union, which Ireland joined soon after Fine Gael came to power in 1973. Mr. FitzGerald served as foreign minister in that 1973-77 government.

“We will remember him for the central role he played both in Ireland and in Irish-European relations, but also for his convictions, his brilliance, his energy, and his friendliness,’’ said José Manuel Barroso, president of the European Commission.

As prime minister between 1981 and 1987, Mr. FitzGerald was unable to reverse a fiscal and economic crisis bequeathed him by the reckless spending of Haughey’s government of the late 1970s.

Ireland suffered double-digit unemployment, heavy emigration, and a losing battle to control deficits during his six years in power.

Fine Gael’s partner in government, union-linked Labor, refused to back Mr. FitzGerald’s austerity plans, and the coalition installed in June 1981 collapsed after eight months. Haughey returned to power but only for nine months, and Mr. FitzGerald returned in 1982, heading another coalition.

After resigning as Fine Gael leader after the party’s election defeat in 1987, Mr. FitzGerald remained active during elections campaigns.

Mr. FitzGerald’s first job after graduating from University College Dublin was to oversee the strategic development of Aer Lingus, Ireland’s national airline.

“Without any of the modern-day analysis tools, Dr. FitzGerald brought his keen economic mind to bear on how to best to plan and utilize aircraft, laying the foundations for the future success of the airline,’’ Aer Lingus said in a statement.

In 1959, Mr. FitzGerald returned to University College Dublin as an economics lecturer, serving there until his election to Parliament a decade later.

He also wrote columns for The Irish Times for 60 years.

“Garret was the renaissance man of our time,’’ said Ireland’s president, Mary McAleese. “His thoughtful writing, distinctive voice, and probing intellect all combined to make him one of our national treasures.

“Above all, Garret FitzGerald was a true public servant,’’ McAleese said. “Steeped in the history of the state, he constantly strove to make Ireland a better place for all its people.’’

A full state funeral is expected to be held next week following Monday’s visit of President Obama.