The article describes the work prepared by the Moscow historian A. V. Ganin, the first scholarly biography of Ya. A. Slashchov, one of the most famous figures of the White movement in Southern Russia, a talented general and a prolific memoirist, the author of classic notes on the defense of the Crimea in 1920 and his relationship with the White dictator, General P. N. Wrangel. Slashchov is an exceptionally bright and charismatic figure, and evaluations of his activities are diametrically opposed, varying from enthusiastic to derogatory. Most clearly, Ya. A. Slashchov realised himself during the defense of the Crimea at the final stage of the Civil War in the South of Russia. A large number of myths have been formed around the figure of the general in memoirs — both about him as a military figure and about an administrator, and about him as a person. Thanks to the involvement of documents from seventeen archives from five countries, the book dispels many stereotypes, and recreates the life and professional path of Ya. A. Slashchov, from birth to death, in detail. Ganin describes unknown pages of Slashchov’s biography, in particular, the details of his service in the Russian Imperial Army, in the Nikolaevskaia Academy of the General Staff, as well as in the Volunteer Army in 1918–1919. The author manages to give a convincing explanation of the reasons for Slashchov’s success in the defense of the isthmuses of Crimea at the turn of 1919–1920. The undoubted merit of the monograph by A. V. Ganin are photographs illustrating a number of aspects of the book, in addition to documentary supplements, among which the memoirs of M. Mezernitskii, a regular soldier, a member of the White movement, who returned to his homeland with Slashchov at the end of 1921.