King John Zápolya of Hungary dies, and his infant son John
Sigismund Zápolya takes the throne. This goes against the treaty of
1538, which promised the succession to Archduke Ferdinand of
Austria and Bohemia. As a result, Ferdinand sends troops into
Hungary to claim the whole country and lays siege to the capital
city of Buda, provoking the intervention of the Ottoman Sultan
Suleiman I.
Citation:
Editors. "The infant John Sigismund Zápolya succeeds as King of Hungary".
The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14642, accessed 19 May 2013.]