 While Wilhelm thought he ruled as emperor in a personal union with Prussia, the constitution actually tied the imperial crown to the Prussian crown, meaning that Wilhelm could not renounce one crown without renouncing the other.Wilhelm's hope of retaining at least one of his crowns was revealed as unrealistic when, in the hope of preserving the monarchy in the face of growing revolutionary unrest, Chancellor Prince Max of Baden announced Wilhelm's abdication of both titles 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.