Former Taoiseach Albert Reynolds reached out to unionists and tried to address their concerns in a way no other Irish leader had ever tried, friends have said.
Retired Church of Ireland Archbishop Lord Robin Eames was one of many who paid tribute to the 81-year-old politician – hailed as a courageous peacemaker – after he died following a long illness.
Lord Eames acknowledged the critical role of Mr Reynolds in delivering the ceasefires of 1994.
"He reached out to the fears in the Protestant/unionist community in a way which was unique at that time and found expression in the Downing Street Declaration through the recognition of (the principle of) consent," he said.
"From my earliest contacts with him, he made this very point – that there were two sides to the process.
"He knew of many of the efforts to bring the loyalists to a ceasefire and encouraged those of us who were working to bring this about and understood the difficulties."
Sir John Major, who signed the 1993 Downing Street Declaration with Mr Reynolds that paved the way for the Good Friday Agreement and lasting peace, remembered him as the leader who made things happen. In a heartfelt message, the former Prime Minister described him as a friend who deserved his place in history.
"Albert Reynolds was at the heart of the success of the Irish peace process. Without Albert, it may never have started – or might have stalled at an early stage – and Ireland, north and south, might still be enduring the violence that scarred daily lives for so long," Mr Major said.
"Albert cared about achieving peace and took risks to deliver a future for Ireland that many thought was impossible. He deserves an honoured place in the history of his country. To me, he became a friend I cherish and will miss."
DUP MP Jeffrey Donaldson said Mr Reynolds helped unionism sell the peace process to its electorate by accepting the principle of consent. "He was the first Irish Prime Minister that really accepted the concept or principle of consent... instead of territorial claims and so on, that it was for the people to decide our destiny," he said.
"He embodied that principle of consent into the Downing Street Declaration and without that I don't believe unionists could have taken forward the other elements of the peace process."
Former US President Bill Clinton said Mr Reynolds had worked hard and risked much to advance the peace process.
"His leadership alongside British Prime Minister John Major was instrumental in laying the foundation for the Good Friday Agreement, and our world owes him a profound debt of gratitude," he said.
Sinn Fein leader Gerry Adams said: "Albert acted on the North (of Ireland) when it mattered."
He was elected to the Irish parliament in 1977 and went on to become Taoiseach in February 1992 in a coalition.
He led Fianna Fail in two coalitions but served less than three years as leader. After surviving a series of political scandals, it was the mishandling of the extradition of paedophile priest Brendan Smyth that brought his time at the top to an end.
He is survived by his wife Kathleen, two sons and five daughters. He had been suffering from Alzheimer's disease.