This publication presents extensive factual material, including information about the history of the creation and development of the Workers' and Peasants' Navy. A special place in the book is given to coverage of the pre-war period in his life. The author has made an attempt, based on the available archival material and the memories of direct participants in hostilities in various naval theaters of the country, to analyze the state and level of training of the Soviet fleets and flotillas, their combat readiness to repel possible aggression. The author convincingly expresses a number of fundamentally new assessments, fundamentally different from the well-known interpretation of some events of the beginning of the Great Patriotic War. The book contains a large number of archival documents, maps, diagrams, drawings and tables. Intended for readers interested in the history of the Russian fleet.