When and how did the Allies find out about the Holocaust, and what were the intelligence sources that delivered the information? This fundamental collection of research studies digs deeply into that sensitive topic and sheds new light on the realities of code-breaking and understanding of what was happening in Nazi-occupied Europe during the Second World War. Documents with their sources have been assembled from many previously closed archives.Includes a preface by David Bankier and an introductory essay by Gerhard L. Weinberg, along with the following international scholars of the Second World War and the Holocaust: David Alvarez, Shlomo Aronson, Peter R. Black, Richard Breitman, Hilary Earl, Tuvia Friling, Norman J.W. Goda, Robert Hanyok, Sebastien Laurent, Katrin Paehler, Stephen Tyas, and Piotr Wrobel.