Albert of Brandenburg, Grand Master of the Teutonic Knights, surrenders the lands of his order to the King of Poland to form a secular, Protestant duchy of Brandenburg, with Albert as duke, under Polish suzerainty.
Editors. "Prussia made a Protestant state by Albert von Brandenburg". The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=9966, accessed 31 March 2015.]