Ferdinand I, King of the Romans (heir to the Holy Roman Empire),
aided by allies such as Joachim II of Brandenburg, had undertaken a
military campaign to try to defend Ferdinand's territory of Hungary
against the encroaching Ottomans, but this campaign is ultimately
unsuccessful.
Citation:
Editors. "The imperial campaign against the Turks in Hungary fails".
The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14672, accessed 19 May 2013.]