Mieszko II Lambert by the chronicles of Gottfried of Viterbo, refers to Bezprym. However, the historians now think that he was killed in a plot hatched by the aristocracy. He was buried in the Cathedral of St. Peter and St. Paul. After Mieszko II's death, Poland's peasants revolted in a "pagan reaction." The exact reasons and date are unknown. Mieszko II's only son and heir, Casimir I, was either expelled by this insurrection, or the insurrection was caused by the aristocracy's expulsion of him. Some modern historians argue that the insurrection was caused more by economic than by religious issues, such as new
Mieszko I of Poland situation at that time. Another debatable point is Thietmar's claim that Mieszko "subordinated himself to the King". Most historians believe that it was only a matter of recognition of Otto's royal authority. Some suggest that a fealty relationship could in fact be involved. Whether or not the German-Polish invasion of Bohemia actually happened, the friendly relations between the Czechs and the Poles came to an end. Bohemia resumed its earlier alliance with the Lutici, which caused in 990 a war with Mieszko, who was supported by Empress Theophanu. Duke Boleslav II was probably the first one to attack. As a