The Diocese of Poznań was erected in 968 as the first diocese in Poland subordinate directly to the Holy See. After 1012, it was incorporated into the Metropolitan Archdiocese of Gniezno. Pope Pius VII raised the diocese to the rank of an archdiocese on 16 July 1821; it formed a personal union with the Archdiocese of Gniezno until 1946. Pope John Paul II introduced territorial changes on 25 March 1992 by the bull Totus Tuus Poloniae populus, and on 24 February 2004.