カノッサの屈辱
Thanks to his support of the papal cause during the investiture controversy in the Holy Roman Empire, Bolesław II gained the royal crown of Poland: on Christmas Day of 1076 Archbishop Bogumił crowned him in the Gniezno Cathedral in the presence of a papal legate. King Henry's IV act of contrition at the Walk to Canossa in 1077 included also the imperial recognition of Bolesław II's royal title. Bolesław's new authority, along with his pride, however, caused the Polish magnates to rebel, as they feared the monarchy had started to grow too powerful.