As the leader of the Social Democratic and Labour Party (SDLP), John Hume helped create the climate that brought an end to violence in Northern Ireland.
When the IRA called a ceasefire in August 1994, it was greeted with jubilation and relief across Northern Ireland.
Despite enormous criticism, Hume always defended his decision to talk to Sinn Féin in order to build that peace process.
While many people were involved, the SDLP leader's role was crucial.
"Politics," he once said, "is the alternative to war."
John Hume's involvement in the cauldron of Northern Ireland politics began on the streets of his home city, Londonderry, where he was born in 1937.
Post-war education reforms enabled him to win a scholarship to the local grammar school and he trained briefly for the priesthood, before returning to work as a teacher.
Drawn into public life, Hume began to campaign on issues such as housing and helped set up a credit union in his native city. But more traumatic times lay ahead.
Despite a majority nationalist population, Derry's council was controlled by unionists - and its reform was among the key demands of the civil rights movement.
Hume lived in the Bogside, scene of some of the earliest confrontations, and he witnessed at first hand the slide from peaceful protest to violent street confrontation.
As the situation in Northern Ireland became worse, he joined with other constitutional nationalists, including Gerry Fitt, in founding the SDLP. Its objective was a united Ireland - but this was only to be achieved by consent.
Nationalist resentment was fuelled by the introduction of internment without trial in 1971.
When a march to an Army camp, where some of the internees were being held, turned to confrontation, it was Hume who voiced the protesters' anger, confronting an Army officer and asking him: "Are you proud of the way your men have treated these people?"
In the years that followed, John Hume's influence continued to grow. Initiatives such as the Sunningdale Agreement, which established a short-lived power sharing assembly involving unionists and nationalists, were a tribute to his campaigning.
In 1985, he played a key role in negotiations over the Anglo-Irish Agreement which for the first time gave Dublin a limited say in the affairs of Northern Ireland.
Elected as the MP for Foyle in 1983, he was also well regarded as a Member of the European Parliament. He had enormous influence in the United States, where he rubbed shoulders with Teddy Kennedy and Bill Clinton.
But it was in direct talks with Sinn Féin President Gerry Adams, which reached a new intensity in 1994, that he took his biggest risk in the search for peace, provoking unionist fury.
The Hume-Adams talks helped pave the way for the historic Downing Street declaration, and the IRA ceasefire months later.
The ceasefire was to last 17 months before being blown apart by a bomb in London's docklands. But, even though the IRA returned to its campaign of violence, the Hume-Adams dialogue continued as multi-party talks began without Sinn Féin in 1996.
The following year saw the election of Tony Blair's Labour government, which agreed to multi-party talks continuing in tandem with the decommissioning of paramilitary weapons.
Sinn Féin was to be invited to participate, provided that the IRA reinstated its ceasefire.
In July 1997, the ceasefire came, followed two months later, by Sinn Fein's inclusion in the talks. Once again, John Hume had been central to momentous events in Northern Ireland.
It did not stop all the violence, as John Hume had hoped, but he was able to argue that hundreds of lives had been saved.
John Hume never lost the conviction that negotiations would in the end provide the solution and, he saw the 1998 Good Friday Agreement as proof of all he had argued for over the years. It was his crowning political moment; the agreement would not have happened without him.
His contribution was recognised with the award of the Nobel Peace Prize which he received jointly with Ulster Unionist leader David Trimble.
Typically, Hume saw the award as an endorsement of the peace process he had done so much to create.
It was his fellow SDLP member Seamus Mallon who assumed the deputy first minister role in the new Northern Ireland Assembly.
John Hume's huge workload took a toll on his health.
In August 1999, he was rushed to hospital while attending a conference in the Austrian resort of Alpbach.
He resigned as leader of the SDLP in September 2001, having been at the helm for 22 years. He said he had suffered from serious health problems and would be cutting down on his workload.
In recent years, John Hume struggled with dementia and had to step away from the public stage.
Speaking in 2018, on the 20th anniversary of the Good Friday Agreement, his wife, Pat, said he had little recollection of the role he had played in Northern Ireland's political life.
"It is very sad, his memory has just gone. John does not remember very much about the agreement of 1998, or about the Anglo Irish Agreement or Sunningdale or anything else," she said.
"Yet he gave his entire life to the achievement of them. But he is in a good place, he is content, he is very happy."
Whatever the subsequent developments in the fractious politics of Northern Ireland, Hume's reputation remained intact.
Along with his Nobel Prize, he was awarded the Gandhi Peace Prize and the Martin Luther King Award, and in 2010 a poll by Irish broadcaster RTÉ named him "Ireland's Greatest Person", beating the likes of Mary Robinson, Michael Collins and Bono to the title.
During a visit to Derry in 2014, former US president Bill Clinton said "this town and John Hume's insistence on non-violence and the embrace of it ultimately by the other parties, notably Sinn Fein" served as an inspiration.
He added: "I implore you, for the sake of the young people and all of those who did so much for so long, like John Hume - finish the job."