He described the 2007 power-sharing agreement as "not hype but history"
Martin McGuinness's departure from elected office brings to an end one of the most improbable chapters of the peace process.
McGuinness (66), a self-confessed former IRA commander and Sinn Féin politician, made the transition to politics and served as deputy first minister for a decade.
He described the 2007 power-sharing agreement between himself and Ian Paisley as "not hype but history".
Sinn Féin leader Gerry Adams said: "People used to say it was a miracle between himself and Ian Paisley, God rest him, and whatever people may think of Martin McGuinness, I'm sure that most people would concede that for 10 years, he broke his back trying to make that office work."
Mr McGuinness joined the IRA in his teens and was convicted of possessing ammunition and explosives.
He admits to having been the IRA's second-in-command, but denies the Bloody Sunday Inquiry finding that he was "probably armed with a sub-machine gun" on the day British troops shot 14 people dead.
Recognising his influence, the British government flew him to London for secret talks in 1972 but the violence continued.
He has repeatedly denied allegations he had advance knowledge of the bombing of Enniskillen's war memorial in 1987.
Following the ceasefire, he was appointed Sinn Féin's chief negotiator in the talks which resulted in the Good Friday Agreement.
A handshake between Britain's Queen Elizabeth II and Mr McGuinness was seen as one of the most symbolic acts of reconciliation- but he knew his journey from guns to government involved risk.
Mr McGuinness said: "If there are people out there who are maliciously disposed towards my involvement in the peace process and they want bad enough to take my life, I'm around long enough to know that they have the ability to do that.
"Am I going to let that put me off in my work for peace? Not in a million years."
Already battling health issues, he resigned as deputy first minister earlier this month in protest at his coalition partner's handling of a costly botched renewable energy scheme.
Brian Rowan, author and journalist, said: "In all the great peace agreements of the world, the men of war become the men of peace.
"And you'll find the Martin McGuinness story on both pages."