Attempts to understand the reasons for the catastrophic defeat of the Red Army in the summer of 1941 were repeatedly made by Soviet and Russian historiographers. However, the research was complicated by the fact that most of the documents of the border divisions, armies and military districts were lost during the fighting. In 1949-1957. The Military Scientific Directorate of the General Staff of the Soviet Army addressed questions about the beginning of the war to the commanders who took part in the first battle on the border. Participants in the events answered the questions posed based solely on memory, without using documentary sources. These materials, published in this publication, remained secret for a long time. Today these documents can be considered one of the most important sources on the initial period of the Great Patriotic War.