The 1940 Summer Olympics were originally awarded to Tokyo. After the outbreak of the second Sino–Japanese War in 1937, they were re–assigned to Helsinki. But they were later cancelled because of World War II.
Similarly, the 1940 Winter Olympics were originally awarded to Sapporo, but on the outbreak of the Sino–Japanese War they were re–assigned to St. Moritz. They were subsequently awarded to Garmisch–Partenkirchen, "due to controversies between the Swiss organizing team and the IOC" (Wikipedia). They were eventually cancelled in November 1939.
The 1944 Olympics were also cancelled because of World War II.
© Haydn Thompson 2017