John Diefenbaker in the context of "Lester B. Pearson"

The Progressive Conservative Party of Canada (PC; French: Parti progressiste-conservateur du Canada) was a centre to centre-right federal political party in Canada that existed from 1942 to 2003.

From Canadian Confederation in 1867 until 1942, the original Conservative Party of Canada participated in numerous governments and had multiple names. In 1942, its name was changed to the Progressive Conservative Party under the request of newly elected party leader Premier John Bracken of Manitoba, a former member of the Progressive Party of Manitoba. In the 1957 federal election, John Diefenbaker carried the party to their first victory in 27 years and the following year, led the party to the largest federal electoral landslide in history. During his tenure, human rights initiatives were achieved, most notably the Bill of Rights. In the 1963 federal election, the party lost power and would not regain it until 1979, when Joe Clark led the party to a minority government victory. The party lost power just nine months later and in 1983, Clark lost his leadership role to Brian Mulroney, who helped the PC Party gain popularity in Quebec. Mulroney won back-to-back majority governments in 1984 and 1988, and during his tenure, major economic reforms such as the North American Free Trade Agreement and the goods and services tax (GST) were introduced.

The 1984 Canadian federal election was held on September 4, 1984, to elect members to the House of Commons of the 33rd Parliament of Canada, following the dissolution of the House on July 9. The Progressive Conservative Party, led by Brian Mulroney, won a landslide victory, defeating the incumbent governing Liberal Party led by Prime Minister John Turner. The Progressive Conservatives won 211 seats, the most seats in the House in Canadian political history, and regained power for the first time since 1979. This was the first election since 1958 in which the Progressive Conservatives won a majority government, and is also the only time since 1958 that Canada's governing party received an actual majority of votes cast. It was also the first election since 1962 in which the Progressive Conservatives won the popular vote.

Mulroney's victory came as a result of his building of a 'grand coalition' that comprised social conservatives from the West, Red Tories from the East, Quebec nationalists, and fiscal conservatives. Winning 74.8 percent of the seats in the House of Commons meant he won the second-largest percentage of seats in Canadian history, with only Progressive Conservative Prime Minister John Diefenbaker's triumph in the 1958 federal election, at 78.5 percent, being higher. This was the last time that the winning party won every province and territory and the last time that the winning party received over 50 percent of the national popular vote. The Liberals suffered what at that time was the worst defeat for a governing party at the federal level (in terms of percentage of seats), until the new record would be set in 1993 by the Progressive Conservatives themselves. The NDP lost a single seat in the House of Commons.