For the first time, a description of a unique book collection exported by Soviet troops from Germany in 1945 as a trophy and scattered among the RSL funds is being published. The rarest books of the king, published in meager editions, are described, as well as books preserved in a single copy. In the appendix to the book, the unknown marginalia of Voltaire and Frederick the Great were first published. The bibliophile edition, richly illustrated, is equipped with a nominal index.