Leonard provides the first comprehensive history of the Red Army's Intelligence Directorate, known today as the GRU, from its inception during the Russian Civil War up to the rise of Nazi Germany in 1933. During these early years of Soviet Army intelligence, the GRU actively promoted Communism internationally through insurrection and partisan warfare. It became deeply involved in espionage in Western Europe, the United States, and Asia. Making extensive use of primary sources, many of which have only recently become available, Leonard completes a story that has until now been often inaccurate or simply confused.