The book of N. D. Postnikov is dedicated to one of the most dramatic events of the First World War - the campaign of the 1st Russian Army in East Prussia in August 1914. Based on numerous archival documents, memoirs and letters of the participants in the war, the author talks about the fate of Russian and German soldiers and officers who participated in bloody battles for East Prussia. The book is designed for specialists and everyone interested in the history of the First World War.