The book is devoted to the problem of the origin of the war between Russia and France in 1812. The focus is on the figure of the "diamond prince," Russian Ambassador to France A. B. Kurakin, who made heroic efforts to reveal the enemy's plans. Based on an extensive set of documents, including the correspondence of A. B. Kurakin with St. Petersburg, various materials deposited in the French and Austrian archives, the author is trying to recreate the diplomatic struggle of the two empires in 1807-1812, full of drama.