 In 1563 his prized general, Wilhelm von Grumbach attacked Würzburg, seized and plundered the city and compelled the chapter and the bishop to restore his lands.He was consequently placed under the imperial ban, but John Frederick II refused to obey the order of the Emperor Maximilian II to withdraw his forces.Meanwhile, Grumbach plotted the assassination of Saxon elector, Augustus; and proclamations were issued asking for assistance.