BREMEN-HAMBURG, ANCIENT DIOCESE OF. — In the year 780 Charlemagne entrusted to the Anglo-Saxon missionary Willehad the region between the Elbe, the city of Norden, and the banks of the lower Weser. Willehad was consecrated bishop of Bremen in 787; his successors were Wille-rico and Leuderico; Bremen was then a suffragan of Cologne. On 1 October 847, at the provincial synod of Mainz, the diocese of Bremen was united with that of Hamburg, and Ansgar became its first archbishop; the city of Hamburg had been founded by Charlemagne in the year 811.
The separation of Bremen from the metropolitan see of Cologne was the cause of disputes that ended at the beginning of the 10th century through the intervention of Pope Sergius III. The two chapters of Bremen and Hamburg were united for the election of the archbishop. Bremen became a missionary center for the countries of northern Europe; as had already been the case with St Ansgar, the archbishops St Rimbert undertook journeys to Denmark and Sweden, as did Archbishop St Unni, who died in 936 at Birka (Sweden). St Adaldag erected the suffragan dioceses of Schleswig, Ribe, and Aarhus in Denmark. The most flourishing missionary period was during the archiepiscopate of Adalbert (1043–1073); in 1104 Pope Paschal II separated the dioceses from Bremen and created the archbishopric of Lund (Sweden). In the 13th century, especially under Archbishop Gerhard of Lippe (1219–58), the two dioceses of Bremen and Hamburg were enriched with religious communities: Augustinians, Benedictines, Carthusians, Cistercians, Premonstratensians, and later Dominicans and Franciscans.
Ancient churches of Bremen: the collegiate church of St Willehad, St Stephen, St Mary, St Ansgar with a tower 97 m high, St Martin. In Hamburg: St Peter, St Nicholas, St James, St Catherine. The last archbishop was Christopher of Brunswick, who was unable to resist the spread of the Lutheran Reformation. Today the territories of Bremen and Hamburg depend on the diocese of Osnabrück.