The book is dedicated to the life and work of one of the outstanding Russian military leaders of the turn of the 18th-19th centuries. Yakov Petrovich Kulnev (1763-1812). He managed to fight under the leadership of the legendary Suvorov, was an associate of Bagration, Barclay de Tolly, Buxgevden, Kamensky, Wittgenstein. He was known and loved by all Russia of that time, highly appreciated by opponents, in particular Napoleon himself, the emperor of France. His death at the beginning of the Patriotic War of 1812 was mourned by everyone. The book was written by an author whose ancestors were closely related to Y. P. Kulnev, in connection with which many previously unknown information and archival documents are given in the historical narrative. The history and genealogy of the Kulnev clan, the biography of the hero's parents, brothers and other relatives are given. The history of his burial and posthumous glory and almost complete oblivion in recent times is given.