After the disastrous Battle of Nicopolis, King Sigismund called for the Sabor in city of Križevci and issued a written guarantee (saluus conductus) stating he would not attempt personal revenge on the opponents or harm them in any way. But, he organised the killing of the Croatian Ban Stephen Lackfi (Stjepan Lacković) and his followers for supporting the opponent king candidate Ladislaus of Naples. The Croatian law dictated that no one could enter the Sabor with arms, so Ban Lackfi and his supporters left their arms in front of the church. Lackfi's supporting troops also remained outside the town. The king's supporters, on the other hand, were already in the church, fully armed. In the turbulent debate that followed, the king's supporters accused Lackfi for treason in the Battle of Nicopolis. Harsh words were used, fight started, and the king's vassals pulled their swords in front of the king, gutted Ban Lackfi, his nephew Stephen III Lackfi, who formerly served as Master of the horse, and the supporting nobility.

Bloody Sabor resulted in Sigismund's fear of the revenge of Lackfi's men, new rebellions of the nobles in Croatia and Bosnia, the death of 170 Bosnian nobles who were killed by Sigismund, and selling off Dalmatia to Venice for 100,000 ducats by Ladislaus of Naples. Finally, after 25 years of fighting, Sigismund succeeded in seizing power and was recognized as a king by means of giving privileges to the Croatian nobility.