The paper presents Graffenauer’s, Alsatian physician and naturalist, stay in Poland as a Napoleonic officer. The authors present the context of Natural History work during the Napoleonic Wars and the biography of this scientist. His writings are analyzed in terms of history of geology. Letters of Graffenauer constitute a precious document for the history of science. The authors emphasize the importance of information about amber, the biography of George Forster, the history of Natural History collection of Gdansk They also highlight the importance of the testimony of the Napoleonic era in the history of Natural Sciences in Poland.