This invaluable work traces the role of the Einsatzgruppen of the Security Police and SD, the core group of Himmler's murder units involved in the "Final Solution of the Jewish Question," during and immediately after the German campaign in Poland in 1939. With carefully selected primary sources contextualized by the authors' clear narrative, this work fills an important gap in our understanding of a crucial period in the evolution of policies directed against Jews, Poles, and others deemed dangerous or inferior by the Third Reich. Supplemented by maps and photographs, this book will be an essential reference and research tool.