ENA history textbook is among the leading didactic tools in school education, and it has the largest circulation among books concerning the past. The knowledge recorded in the textbooks influences present mutual perceptions, which is particularly significant in the case of neighbors. On the basis of analysis of selected Polish textbooks of history we have investigated how the following episodes were presented at various times: the Union of Krewa, the Battle of Tannenberg and the Union of Lublin. A variety of factors affect the manner in which these events, related to the initial period of Polish and Lithuanian relations, are presented. They include: the form of the author’s narration, current political situation, and the state of historical research, to name but a few. We can observe the most significant changes in the assessments of the same historical facts, which are mainly influenced by the raison d ’estat that transforms in time. Therefore, whenever a textbook is written, Polish authors assessing the victory at Tannenberg refer to the success of the Polish and Lithuanian armies, whereas the Lithuanian authors refer to the Lithuanian and Polish troops in this order. It is important with respect to textbooks that both sides acknowledge that in the case of profound differences, as it is in the case of the Union of Lublin, the students need to be informed what interpretation of certain historical events can be encountered by their counterparts across the border. This is in concordance with current trends in historical education in schools.