German Empire
The high command under Paul von Hindenburg and Erich Ludendorff increasingly controlled the country, but in October after the failed offensive in spring 1918, the German armies were in retreat, allies Austria-Hungary and the Ottoman Empire had collapsed, and Bulgaria had surrendered. The Empire collapsed in the November 1918 Revolution with the abdications of its monarchs. This left a postwar federal republic and a devastated and unsatisfied populace, which later led to the rise of Adolf Hitler and Nazism.
Constitution of the German Empire
The empire was officially defined as a federation of the member states under the presidency of Prussia. The King of Prussia was automatically the bearer of the "Bundespräsidium", since 1 January 1871 additionally with the title "German Emperor" ("Deutscher Kaiser"). Therefore, the imperial crown was tied to the "office" of the King of Prussia instead of a personal union between the Empire and Prussia. This meant that contrary to what Wilhelm II believed at the end of World War I, he could not abdicate merely as German Emperor while keeping the Prussian crown unless he agreed to renounce the entire constitution, which would have been, in effect, the "de jure" dissolution of the Empire.