The term "German Emperor" refers to the monarch who ruled over the German Empire from its unification in 1871 until the end of World War I in 1918. The title was held by the Kaiser, who was also the King of Prussia. The first German Emperor was Wilhelm I, and the last was Wilhelm II. The German Empire was a federal state that included various German-speaking territories. The Emperor had significant powers, but the empire also had a parliamentary system with a Reichstag, which represented the interests of the German states. The monarchy ended with the abdication of Wilhelm II following Germany's defeat in the war.