On 20 July 1944, Adolf Hitler and his top military associates entered the briefing hut of the Wolf's Lair military headquarters, a series of concrete bunkers and shelters located deep in the forest of East Prussia, not far from the location of the World War I Battle of Tannenberg. Soon after, an explosion killed three officers and a stenographer, injuring everyone else. This assassination attempt was the work of Colonel Claus von Stauffenberg, an aristocrat who had been severely wounded while serving in the North African theater of war, losing his right hand, left eye, and two fingers of his left hand.