The former anti-apartheid campaigner was released from prison in February 1990 by FW de Klerk, the country's last white president, after 27 years behind bars.
During that time Mandela had come to symbolise South African's resistance to racial oppression and had acquired the moral stature to negotiate the end of apartheid and the birth of democracy, without the civil war that millions of South Africans had feared as inevitable.
According to Blair, it was Mandela's willingness to negotiate with his former captors that "changed the course of South Africa's history".
"He was the only person who could have accomplished South Africa's transition to majority rule in a peaceful way, because of his own extraordinary life," Blair says.
"He spent 27 years in prison. That meant two things - first of all no-one could doubt his dedication to the struggle; and second no white South African could doubt that his gestures of reconciliation were genuine, that they were heartfelt."
Mandela was elected South Africa’s first black president in 1994. His inauguration as president was attended by over 100,000 people of all races.
Read the story of Mandela's tempestuous life, filled with hardship and struggle and crowned by a singular triumph, in The Telegraph's seven-part obituary.
1. Nelson Mandela obituary: one of the most inspiring figures of the 20th century
2. Nelson Mandela obituary: stirring up trouble
3. Nelson Mandela obituary: domestic and political strife
4. Nelson Mandela obituary: a marked man
5. Nelson Mandela obituary: imprisoned on Robben Island
6. Nelson Mandela obituary: guiding South Africa from apartheid to democracy
7. Nelson Mandela obituary: truth and reconciliation
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