"The Making of the Atomic Bomb" refers to the development of nuclear weapons during World War II, primarily through the Manhattan Project. This secret research initiative involved scientists from the United States, the United Kingdom, and Canada, who worked together to harness nuclear fission. Key figures included J. Robert Oppenheimer, who led the project, and Enrico Fermi, who contributed to the first controlled nuclear chain reaction. The project culminated in the creation of two types of atomic bombs: one using uranium-235 and the other using plutonium-239. These bombs were dropped on the Japanese cities of Hiroshima and Nagasaki in August 1945, leading to Japan's surrender and the end of World War II.