Editors. "Schmalkaldic strongholds submit to Charles V". The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14749, accessed 20 April 2014.]
The city of Ulm, which had been a stronghold of the Schmalkaldic League, submits to the forces of Charles V. On 29th, Frankfurt does the same, in a series of defeats for the League.