Free state, Germany, formerly seat of an archdiocese. It was made a bishopric with Willehad as first bishop, 787. In 848 it united with Hamburg, and two centuries later the archiepiscopal see was transferred to Bremen. The work of converting the northern tribes was carried on from the city. It was burned by the Hungarians, 918. The temporal power of the archbishops, beginning with Adalbert (1043-1072), included all the countships in the diocese, but declined during the 14th century. Bremen was a center of the Reformation, and joined the Smalkaldic League; by the 16th century the cathedral chapter had become Protestant. The revival of Catholicism in 1625 was temporary, for the archdiocese was captured by the Swedes, who secularized it, 1648, and suppressed the cathedral chapter. In 1712 it belonged to Denmark, and in 1715 it was purchased by Prince George of Hanover. In 1731 it was recognized as a free city; it joined the German Confederation, 1815, the North German Confederation, 1866, and the German Empire, 1871. A greater part of it was ceded to Hanover. Ecclesiastically the state is divided among several dioceses; the city and vicinity is subject to the Vicar Apostolic of Northern Missions, and the remaining territory to Hildesheim, Osnabrück, and Münster.