ENAt the Council of Constance, the issue of the Christianisation of Lithuania and Samogitia came to the fore in the dispute between the Polish-Lithuanian Union and the Teutonic Knights. The whole matter was brought about by a Polish-Lithuanian delegation (1416), which in two indictments, Proposicio Polonorum and Proposicio Samagitarum, accused the Grand Master and the Order of hostility towards the recently baptised Lithuanians and against the Samogitians, who had expressed the same willingness to accept the Catholic faith. On the contrary, the Order's delegation, calling on its own historical experience, accused the dukes of Lithuania, including King Vladislav Jagello of Poland, of hypocrisy, dishonesty and treachery. Surprisingly, the Order's reply does not call into question the very fact of the mass baptism of Lithuanians, who willingly accepted Christianity, but doubted their simple-mindedness and inability to understand the content of the creed and the significance of the ceremony they had undergone. The Polish-Lithuanian party's argument was more successful because it was based on numerous biblical motifs, such as the light and peace that Jesus Christ brought to earth and which were desired by the pagans in Lithuania and Samogitia. On the contrary, the political and historical arguments of the Order's delegation lacked a similar positive emotional charge. The practical long-term consequence of the controversy was the official baptism of the Samogitians, the establishment of a diocese (1417) and the permanent annexation of the disputed territory to Lithuania. Keywords: Council of Constance; Christianization of Lithuania; Polish-Lithuanian-Teutonic controversy; Baptism; Samogitians; polemical treatises. [From the publication]