The Manhattan Project

The United States in late 1941 established a secret program, which came to be known as the Manhattan Project, to develop an atomic bomb, a powerful explosive nuclear weapon. The aim of the project, directed by physicist J. Robert Oppenheimer, was to build an atom bomb before Germany did.

After Otto Hahn's and Fritz Strassman's discovery [nuclear fission] it became evident that sooner or later some country would make an atom bomb

Joseph O. Hirschfelder, chemist