Between 1921 and 1947 it was nuclear physics, more than any other science, that shaped both the political landscape of our century and the public opinion on physical research. Using quantitative scientometric methods, a new branch in the history of science, the author focuses on the developments of nuclear physics in these formative years, paying special attention to the impact of German emigrants on the evolution of the field as a cognitive and social unity. The book is based on a thorough analysis of various citation analyses, thus producing results that should be both replicable and objective. The scientometric techniques should complement the more qualitative approach usually applied in historical writing. This makes the text an interesting study also for the historians in general.