Infantry Regiment 9 of Potsdam (I.R. 9) was an infantry regiment in Weimar Republic's Reichswehr and Nazi Germany's Wehrmacht, descended from famed 1st Prussian Regiment of Foot Guards in the German Empire's Deutsches Reichsheer. Garrisoned at the cradle of Prussian army and rich with tradition, it was nicknamed 'Count Nine' (Graf Neun) or 'I.R. von 9' by its detractors because of high percentage of Prussian aristocrats and purported arrogance in its ranks. Today it is most remembered for the fact that nineteen of its officers (or former officers) were involved in conspiracy against Hitler, more by far than any other German regiment. Most of them were executed or committed suicide after the failure of the 20 July plot to assassinate Hitler. Major General Henning von Tresckow and Lieutenant Colonel Fritz-Dietlof von der Schulenburg in particular were central figures in German resistance. The regiment's tradition is continued by the Wachbataillon of the Bundeswehr.

Officers who conspired against Hitler

Lieutenant Colonel Hasso von Boehmer Major Axel Freiherr von dem Bussche-Streithorst Captain Dr. Hans Fritzsche Lieutenant Colonel Helmuth von Gottberg Lieutenant Colonel Ludwig Freiherr von Hammerstein Lieutenant Colonel (res.) Carl-Hans Graf von Hardenberg Lieutenant General Paul von Hase Lieutenant Ewald Heinrich von Kleist Colonel Hans Otfried von Linstow Captain Friedrich Karl Klausing Major (res.) Ferdinand Freiherr von Lüninck Major (res.) Herbert Meyer Lieutenant Georg-Sigismund von Oppen Major Kurt Freiherr von Plettenberg Colonel Alexis Freiherr von Roenne Lieutenant Colonel (res.) Fritz-Dietlof von der Schulenburg Lieutenant Colonel Gerd von Tresckow Major General Henning von Tresckow Lieutenant Colonel i. G. Hans-Alexander von Voß Captain (res.) Achim Freiherr von Willisen Colonel Claus von Stauffenberg Captain (res.) Richard von Weizsäcker