The Manhattan Project was a secret research and development program during World War II aimed at creating the first nuclear weapons. Initiated by the United States with support from the United Kingdom and Canada, it began in 1942 and involved some of the world's top scientists, including Robert Oppenheimer and Enrico Fermi. The project led to the successful development of two types of atomic bombs, which were dropped on the Japanese cities of Hiroshima and Nagasaki in August 1945. This event played a significant role in bringing about the end of World War II and marked the beginning of the nuclear age.