Dietrich commanded the 1st SS Panzer Corps in the Battle of Normandy. He rose to command 5th Panzer Army during the later stages of this campaign. Hitler gave him command of the newly created 6th Panzer Army. Dietrich led it in the Battle of the Bulge (December 1944-January 1945). He had been assigned to that task because, due to the 20 July Plot, Hitler distrusted Wehrmacht officers. On 17 December, "Kampfgruppe Peiper"—an SS unit under his overall command—murdered 84 U.S. prisoners of war near Malmedy, Belgium, in what is known as the Malmedy massacre.