The federal Conservatives under Stephen Harper underestimated Justin Trudeau's political strengths, and their mistake ended up "biting" them, former Conservative prime minister Brian Mulroney says.

Mr. Mulroney says he warned the Conservatives for years that they shouldn't take their Liberal opponent lightly, and he cautioned them that Mr. Trudeau is very different from previous Liberal leaders who went down to defeat at Mr. Harper's hands.

The Conservatives fired barrages of attack ads at Mr. Trudeau, as they had previously done with great effectiveness against earlier Liberal leaders, but Mr. Trudeau shrugged off the attacks and won a majority in October's election.

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"With all due respect to Messrs. Stephane Dion and Michael Ignatieff, Justin Trudeau is neither," Mr. Mulroney told The Globe and Mail in an interview in Johannesburg. "He is his own man."

He said he cannot understand the Conservative failure to take Mr. Trudeau seriously enough. "When you underestimate your opponent in politics, you run the risk of it coming back and biting you."

Mr. Mulroney, who is in South Africa to receive one of the country's highest honours for his anti-apartheid work in the 1980s, has been warning the Tories since 2012 that they would underestimate Mr. Trudeau "at their peril." He said he made the point repeatedly in private conversations with politicians and in media interviews, beginning with an interview with The Globe and Mail in October, 2012. But he said he doesn't know why his advice was disregarded.

Mr. Mulroney, the last Conservative leader to win a majority government before Mr. Harper, also predicted that Mr. Trudeau will lead a resurgence in Canadian activity in Africa, a region neglected by Mr. Harper's government for most of its term.

"My guess is that there will be a revival of interest," he said. "My guess is that Mr. Trudeau is quite an internationalist, and he is going to be quite taken by the opportunities and challenges here in Africa."

Canada's economic strengths and development expertise "could be put to good use" in Africa, he said.

Mr. Mulroney, who led an international campaign to impose sanctions on South Africa's apartheid regime in the late 1980s, has been appointed as a gold member of the Order of the Companions of O.R. Tambo – the highest South African honour for foreign citizens. He will receive the award from President Jacob Zuma in a ceremony on Tuesday.

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The honour is being awarded to Mr. Mulroney "for his exceptional contribution to the liberation movement of South Africa," Mr. Zuma said. "His steadfast support for the release of Nelson Mandela and for imposing sanctions on South Africa's apartheid regime led to a free, democratic, non-sexist and non-racial South Africa."

On Monday, Mr. Mulroney and his wife Mila visited the foundation in Johannesburg that holds the archives of Mr. Mandela, the anti-apartheid struggle hero who became South Africa's first democratically elected president. They examined his Nobel Peace Prize, admired a hand-carved Haida gift to him, and read some of his handwritten letters to his daughters from his Robben Island prison cell.

The letters, some of which never reached his family because of prison censorship, showed that the "mental torture" inflicted by the apartheid regime was often worse than its physical brutality, Mr. Mulroney said.

Stephen Lewis, the Canadian ambassador to the United Nations under Mr. Mulroney, says he is convinced that Mr. Mulroney "played a decisive role in bringing down the apartheid regime" by pressing for economic sanctions against the white-minority government.

"No one should ever minimize Brian Mulroney's passion for overturning apartheid," Mr. Lewis said by e-mail. "He genuinely thought it one of the most evil systems on the planet. He had a real feeling for Mandela, and desperately wanted him out of jail, understanding that with Mandela's freedom came South Africa's liberation."

Mr. Mulroney's championing of economic sanctions led to a famous clash with British prime minister Margaret Thatcher at a Commonwealth meeting in Vancouver in 1987. "I'll never forget the way he went after Margaret Thatcher… with all the African leadership in the room," Mr. Lewis said.

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"It was scathing, unforgiving and memorable. I don't think Thatcher had ever received such a tongue-lashing in her entire political life. I loved it. So did everyone else. He deserves the honor that South Africa is conferring upon him. And he won the lasting, devoted friendship of Nelson Mandela."

Mr. Mulroney still vividly recalls his battle with Mrs. Thatcher over the sanctions issue. "She was livid," he said in the interview. "She was very irritated by Canada's position."

One key reason for her opposition to sanctions was the potential impact on the large number of British investors in South Africa, he said. "I said, 'Margaret, that's silly. Morality is not measured in dollars and cents. Something is either right or wrong.'"

Mr. Mulroney also faced opposition from some MPs in his own caucus who believed that Mr. Mandela was a terrorist and a communist. "I had to persuade them that we were doing the right thing," he said. "I asked some of them to come and see me. I said, 'I want you to know, there's going to be no room in the Progressive Conservative caucus for someone who holds those views.'"

Mr. Mulroney's critics, including some scholars and historians, have argued that Canada was late to the anti-apartheid movement and never moved beyond symbolic and rhetorical opposition to the apartheid regime. Canada, for example, never imposed comprehensive mandatory sanctions on the apartheid regime, preferring instead a voluntary code of conduct for Canadian investors and narrow bans on trade in a few sectors.



Critics also cite Mr. Mulroney's frosty meetings with leaders of Mr. Mandela's political movement, the African National Congress, including Oliver Tambo – the man whose achievements inspired the award that Mr. Mulroney is receiving on Tuesday. The federal Conservatives were suspicious of "violent" tendencies in the ANC, and this contributed to the chilly reception that Mr. Tambo received from the Conservative government.

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Mr. Mulroney argues, however, that he was mostly concerned about the "necklacing" attacks by some ANC members – the gruesome killings in which "traitors" were set ablaze with burning tires around their necks. This is what led to his verbal conflict with Mr. Tambo and other ANC leaders, he said.

"Joe Clark and I called them in, and we had some words with ANC leaders. We said, 'This stuff has got to stop. It's damaging your reputation and eviscerating our capacity to be of assistance to you.' Tambo was there, and he said, 'I'll fix it.' And that was it."