Answer
In 1940, Otto Frisch and Rudolf Peierls wrote a memorandum to British physicists on the feasibility of an atomic bomb. They concluded that it was possible to build a bomb that would release the energy of the atomic nucleus, but that it would require a large amount of uranium-235. The Frisch–Peierls memorandum was a key factor in the British decision to begin the Manhattan Project to develop an atomic bomb.