The article focusses on German military intelligence on the home front during World War I. Although the German General Staff had intensified its intelligence activities prior to 1914, its preparations for war proved to be insufficient after the beginning of the war. Before the war, Department IIIb of the General Staff had almost exclusively dealt with espionage and counter-espionage. By the armistice its tasks by far exceeded this: in addition to being an espionage and counter-espionage service, by 1918 it also was a political police, a censorship and propaganda authority, it issued identity cards and organized postal censorship.