The crisis in Polish-Lithuanian relations in the last years of the reign of Władysław II Jagiełło (Jogaila), caused by the coronation efforts of Vytautas the Great and later by Švitrigaila’s attempts to break up the union and achieve the full sovereignty of Lithuania, resulted in the parties presenting their arguments on the international arena in the speeches of deputies at the Reichstag in Nuremberg or to the Papal Curia, but also in the correspondence circulating between the courts of rulers, manifestos issued and consilia prepared by scholars. The use of letters and manifestos as a tool to present and promote the right to power became very evident during the dispute between natural brothers Władysław II Jagiełło and Švitrigaila. And it was not a matter of convincing each other between the conflicting parties or making them aware of the situation, but of outlining their reasons before external parties. In letters addressed to the Grand Master of the Teutonic Knights, King Władysław II wrote about the inheritance of power from his father and referred to the Lithuanian-Ruthenian rule as his heritage, calling the Grand Duchy of Lithuania his verum et legittimum patrimonium. His youngest brother similarly defended his power by referring to its basis. In the Vitebsk manifesto of March 1433 addressed to the Council of Basel, Švitrigaila’s loyal subjects drew attention primarily to the consensual election of the prince on Jogaila's advice and guidance, completely ignoring the question of hereditary rights. Moreover, in the light of the statement of the prince's Ruthenian subjects, it was only the legitimate election of Švitrigaila that made him verus heres. One of the letters presented at the council by Švitrigaila’s spokesmen, full of misrepresentations and accusations against Jogaila, led to a clash between Polish and Teutonic (as well as Švitrigaila’s) advocates. The exchange of letters, manifestos and consilia and the discussion that took place around the arguments raised in them regarding the right to succession and power in the Jagiellonian monarchy shaped the political culture of the elites and established the role of writings in it.