World War II: First Québec Conference of Winston Churchill, Franklin D. Roosevelt, and William Lyon Mackenzie King begins.

The First Quebec Conference, codenamed Quadrant, was a highly secret military conference held during World War II by the governments of the United Kingdom, Canada, and the United States. It took place in Quebec City on August 17–24, 1943, at both the Citadelle and the Château Frontenac. The chief representatives were Winston Churchill and Franklin D. Roosevelt, hosted by the Canadian prime minister William Lyon Mackenzie King.

Sir Winston Leonard Spencer Churchill was a British statesman, military officer, and writer who was Prime Minister of the United Kingdom from 1940 to 1945 and again from 1951 to 1955. For some 62 of the years between 1900 and 1964, he was a member of parliament (MP) and represented a total of five constituencies over that time. Ideologically an adherent to economic liberalism and imperialism, he was for most of his career a member of the Conservative Party, which he led from 1940 to 1955. He was a member of the Liberal Party from 1904 to 1924.

Franklin Delano Roosevelt, also known as FDR, was the 32nd president of the United States from 1933 until his death in 1945. He is the longest-serving U.S. president, and the only one to have served more than two terms. His first two terms were centered on combating the Great Depression, while his third and fourth saw him shift his focus to America's involvement in World War II.

William Lyon Mackenzie King served as the tenth prime minister of Canada for three non-consecutive terms from 1921 to 1926, 1926 to 1930, and 1935 to 1948. A Liberal, he was the dominant politician in Canada from the early 1920s to the late 1940s. With a total of 21 years and 154 days in office, he remains the longest-serving prime minister in Canadian history.