In Germany, the two opposing groups of princes, the Catholic League
and the Protestant Union, sign an agreement at Mülhausen. The
princes of the League promise not to seize or attack the lands of
the Protestant administrators of the Empire, or the secularised
lands in north Germany, 'so long as the holders still act as loyal
subjects of the Emperor'.
Citation:
Editors. "The Catholic League and the Protestant Union sign an agreement".
The Literary Encyclopedia. First published 01 February 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=15842, accessed 19 May 2013.]