"Willehad" fixed his headquarters at Bremen, though the formal constitution of the diocese took place only after the subjugation of the Saxons in 804 or 805, when "Willehad"'s disciple, Willerich, was consecrated bishop of Bremen, with the same territory. The diocese was conceivably at that time a suffragan of the archbishops of Cologne, this is at least how they later corroborated their claim to supremacy over the Bremian see. When, after the death of Bishop Leuderich (838–45), the see was given to Ansgar, it lost its independence, and from that time on was permanently united with the "Archdiocese of Hamburg".