This collection includes documents that reveal the process of developing recommendations on improving the Red Army based on the experience of the Soviet-Finnish war of 1939-1940. The collection publishes proposals from all specialized commissions and subcommittees of the Main Military Council of the Red Army, created after a meeting in the Kremlin on April 14-17, 1940 to summarize the experience of the “winter war”, as well as transcripts, minutes and minutes of meetings of the commission of the Main Military Council, on which discussed issues of arming the Red Army, organizing military exercises and maneuvers, and military ideology. The work carried out in the Red Army, taking into account the experience of the “Winter War,” directly affected its condition before another war, which began on June 22, 1941. In this regard, the documents of the collection published for the first time significantly expand the source base of scientific research both on the history of the “Winter War” and and on the prehistory of the Great Patriotic War of 1941–1945. The book is intended for specialist researchers of Russian history and for a wide range of readers.