„A niechaj już unijej w skrzyniach nie chowamy” – akty unii lubelskiej i horodelskiej z archiwum Wielkiego Księstwa Litewskiego w zbiorach Radziwiłłów

The article discusses the preservation history of two copies of the Union of Lublin act, the fate of which is unknown. These were: the second copy of the Lithuanian side’s act issued for the Polish Crown and the act of the Union handed over by the Polish side to Lithuanians. In the course of describing the history of the acts of the Union of Lublin, the author also describes the fate of several documents directly related to the Union of Lublin, contained in the Radziwiłł collection. Since the times of Nyasvizh and Kleck fee holder Antoni Wilhelm Radziwiłł (1833–1904), the acts of the Union of Lublin were kept under supervision in a special box which also contained the acts of the Union of Horodło. For this reason, the article also presents the course of preservation of the Union of Horodło. The author of the article puts forward a hypothesis that the acts of both the Union of Horodło and the Union of Lublin from the Radziwiłł collection were burnt in Warsaw together with the Krasiński fee library in the first half of October 1944.