Famous Russian historian, talented publicist, white emigrant Sergei Petrovich Melgunov (1879-1956) in his book "The Golden German Key of the Bolsheviks" (1940) opens the veil of secrecy over one of the secret pages of the history of the October Revolution. He explores the topic of financing by the Germans of the Bolshevik party, led by V. I. Lenin during the preparation and implementation of the October Revolution. In his book, Melgunov analyzes and brings together the random publications and memoirs of those who were related to the events. His conclusion is striking: the Bolsheviks were subsidized by the Germans, and moreover, without their support, the revolution could not have taken place.