The bomb projects

In March 1940, German physicists Rudolf Peierls and Otto Frisch wrote to the British government in their Memorandum on the Properties of a Radioactive 'Super-Bomb', urging them to take action. It led to the British bomb project, codenamed Tube Alloys.

The US government appointed physicist Arthur Compton to lead a nuclear weapons programme, eventually named the Manhattan Project. Over the next four years, the US, UK and Canada poured resources into the Manhattan Project. Tube Alloys was eventually joined with the US project.