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.
Oldenburg
After German Emperor Wilhelm II was forced to abdicate following the exhaustion and defeat of the German Empire in World War I, monarchic rule ended in Oldenburg as well with the abdication of Grand Duke Frederick Augustus II of Oldenburg "()" on 11 November 1918. The Grand Duchy now became the Free State of Oldenburg "()", with the city remaining the capital.