Gutsy Spence, one of the founding members of the pro-British Ulster Volunteer Force (UVF), an organisation responsible for hundreds of murders in the British-controlled province's 30-year sectarian conflict, was instrumental in ending its campaign.
In 1966, the UVF "declared war" on the Irish Republican Army (IRA), which wanted Northern Ireland to sever its connection to Britain and unite with the Republic of Ireland.
In June of that year, the UVF killed their first Catholic victim. Spence was charged with the murder but the charges were dropped.
Later that year, Spence was given life in prison for the murder of an 18 year-old Catholic barman, Peter Ward.
In his 18 years behind bars, Spence turned away from violence and on his release, he became involved in politics.
In 1994, he read out the statement announcing that the UVF and another paramilitary group, the Ulster Defence Association, were declaring a ceasefire in response to an IRA cessation.
He insisted on including an apology in the statement and said the pro-British paramilitaries offered "abject and true remorse" to the families of all their victims.
The words helped set the tone for the peace process.
Despite several years spent out of public life, Spence was asked by the UVF in 2007 to announce the organisation was decommissioning its weapons.
The UVF has continued to carry out sporadic shootings since 2007, something Spence, who died in hospital in East Belfast at the age of 78, condemned.
A former leader of the Progressive Unionist Party, which is linked to the UVF, said Spence's contribution to peace in Northern Ireland was "incalculable."