The city of Magdeburg had adopted the Reformation in the 1520s, and
taken part in the Schmalkaldic League. After the League's defeat in
the war against the Emperor of 1546-7, it refused to accept the
Augsburg Interim and was put under the ban of the Empire. In
September 1550 Charles V sent Duke Maurice of Saxony to besiege the
city, but only in November 1551 did its citizens submit.
Citation:
Editors. "Magdeburg capitulates to Maurice of Saxony".
The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14824, accessed 19 June 2013.]