 Complete the following phrase:  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 on. 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 