Gustavus II of Sweden signs a military convention with the Elector
of Brandenburg, but this comes too late to save Magdeburg from the
besieging imperial forces of Pappenheim and Count Tilly.
Citation:
Editors. "Gustavus II signs a military convention with the Elector of Brandenburg".
The Literary Encyclopedia. First published 01 February 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=16019, accessed 18 June 2013.]