Christian Wilhelm was a son of Elector
Joachim Frederick of Brandenburg (1546-1608) from his first marriage with
Catherine (1549-1602), a daughter of Margrave
John of Brandenburg-Küstrin (1513-1571). He was elected as Archbishop of Magdeburg in 1598. However, the city of Magdeburg did not recognize him as
Prince-Bishop, because his election had not been confirmed by the emperor. When he married in 1614, he assumed the title of
Lutheran administrator only. That same year, he also became coadjutor of
Halberstadt. In 1624, he became administrator of Halberstadt. During the
Thirty Years' War, he entered into an alliance with Denmark. In 1626, he led an army from Lower Saxony into the
Battle of Dessau Bridge. After
Wallenstein won this battle, he fled abroad. In 1629, he fled to the court of King
Gustavus Adolphus of Sweden. In 1630, he returned to Germany. The
cathedral chapter of Magdeburg formally deposed him in 1631. Sweden promised to assist him when he attempted to reconquer his Archbishopric. Nevertheless, the reconquest failed and he was badly injured during the siege of Magdeburg in 1631. He was taken up in the army camp
Pappenheim, where his wounds were tended and
Jesuits persuaded him to convert to
Catholicism. A pamphlet with the title was published in his name, and he was released. Under the
Peace of Prague of 1635, he received an annual sum of taler from the revenues of the archbishopric of Magdeburg, plus the districts
Loburg and
Zinna. In 1651, he purchased the
Nový Hrad estate in Bohemia. He died at
Zinna Abbey in 1665. ==Personal life==