Casimir I the Restorer not supported by modern historians. Regardless, he left church work for good in 1031. Casimir's father, Mieszko II, was crowned King of Poland in 1025 after the death of his father Bolesław I the Brave. However, the powerful magnates of the country feared a strong central government like the one that existed under Bolesław I's rule. This led to considerable friction between the King and the nobility. Taking advantage of the King's precarious situation, Mieszko II's older half-brother Bezprym and younger brother Otto turned against him and allied themselves with the Holy Roman Emperor Conrad II, whose forces attacked Poland
Mieszko I of Poland to the Warta River). In all probability Mieszko decided to pay tribute in order to avoid an invasion similar to the one that Lusatia had suffered. This homage would take place in 965, or in 966 at the latest. Very likely the tribute applied only to the Lubusz land, which was in the German sphere of influence. This understanding of the tribute issue explains why already in 967 Mieszko I was described in the Saxon chronicles as the Emperor's friend (or ally, supporter, Latin: "amicus imperatoris"). Probably in 964 Mieszko began negotiations with the Bohemian ruler Boleslav I the Cruel.