"After the outbreak of the German Revolution, Wilhelm could not make up his mind whether or not to abdicate. Up to that point, he was confident that even if he were obliged to vacate the German throne, he would still retain the Prussian kingship. The unreality of this belief was revealed when, for the sake of preserving some form of government in the face of anarchy, Wilhelm's abdication both as German Emperor and King of Prussia was abruptly announced by the Chancellor, Prince Max of Baden, on 9 November 1918. (Prince Max himself was forced to resign later the same day, when it became clear that only Friedrich Ebert, leader of the SPD could effectively exert control.)"
From "Wilhelm II, German Emperor" (http://en.wikipedia.org/wiki/Wilhelm_II,_German_Kaiser#Abdic...):
"After the outbreak of the German Revolution, Wilhelm could not make up his mind whether or not to abdicate. Up to that point, he was confident that even if he were obliged to vacate the German throne, he would still retain the Prussian kingship. The unreality of this belief was revealed when, for the sake of preserving some form of government in the face of anarchy, Wilhelm's abdication both as German Emperor and King of Prussia was abruptly announced by the Chancellor, Prince Max of Baden, on 9 November 1918. (Prince Max himself was forced to resign later the same day, when it became clear that only Friedrich Ebert, leader of the SPD could effectively exert control.)"