This is the first book-length study of the life and career of the Israeli chemist Ernst David Bergmann. It traces his birth and education in Germany; his decision, after the rise of Hitler, to immigrate to Palestine rather than to accept a position at Oxford; and his intimate 18-year association with Chaim Weizmann – not only as his closest scientific associate but also as Scientific Director of both the Sieff Institute and of the Weizmann Institute. Also described is his tragic falling out with Weizmann over the issue of the role of science in defense research, leading to his subsequent 18-year association with David Ben-Gurion as his personal science advisor and as Head of Scientific Research for the Israeli Defense Ministry, and to his pivotal role in the development of the Israeli atomic bomb. For the last 23 years of his life Bergmann also served as Professor of Organic Chemistry at the Hebrew University, where he trained a generation of Israeli chemists, as well as playing a key role in the organization of virtually every aspect of the present-day Israeli scientific community.