The article presents the significant role of director Marian Pelczar in the post-war rescuing of the collections of the Municipal Library in Gdansk (currently Gdansk Library of the Polish Academy of Sciences). The actions related to the protection of book and manuscript collections after the Second World War were of key importance for the reconstruction of the Polish libraries and library science. Of particular importance was the period from 1945 until 1946, when the fate of the physical survival of many library materials hung in the air. Dr Marian Pelczar lavished tender care on the most precious collections of the Municipal Library and managed to extend them to include fragments of historical books and manuscripts from the region of Pomerelia. Acting during the exceptionally difficult post-war times, he contributed to the preservation of the precious heritage of regional, domestic, and European written culture of various provenance.