Multiple assassination attempts were made against Adolf Hitler, but the "20th of July Plot" was the only one in which he was injured, and the only one where a serious coup attempt was made. The actual attack was a bomb, placed in Hitler's conference room, by Colonel Claus von Stauffenberg, chief of staff of the Ersatzheer (Reserve Army). A key element was that Army staff officers planned to seize control of the governance apparatus by invoking Operation Valkyrie, a contingency plan against internal disorder.
Aside from attempts by individuals such as Georg Elser, there had been attempts by individual military officers or small groups. This attempt was far more significant, as it had a plan to gain control. Indeed, it has been argued that the coup might have succeeded even if Hitler had not been killed, but the conspirators were much more aggressive in taking action.
The chief planners were Stauffenberg, Friedrich Olbricht, and Olbricht's chief of staff, Albrecht von Mertz von Quirnheim.[1]
On July 15, 1944, Stauffenberg planned to stage a second assassination attempt against Hitler. When Heinrich Himmler and Hermann Goering, were not present, Generals Ludwig Beck told him not to carry out the attack. While Stauffenberg and Quirnheim agreed to go after Hitler in any event, Hitler was gone from the conference room when he returned.
Col. Claus von Stauffenberg, accompanied partially by his aide, Lt. Werner von Haeften, was to attend Hitler's daily conference. Normally, this was held in an underground bunker that would concentrate the blast of the bomb he had concealed in a briefcase, but the weather encouraged use of an above-ground facility.
The bomb-laden briefcase had been placed next to Hitler, against the massive leg of the conference table. A staff officer, pointing at the map on the table, found the briefcase in his way and moved it to the side away from Hitler.
Quirnheim and Olbricht, on the first warning, issued the first teletype Operation Valkyrie directives sent to all military bases. The orders announcing Hitler's assassination and the army's seizure of power under Field Marshal Erwin von Witzleben.[1]
When Gen. Erich Fellgiebel learned that Hitler had survived, he shut down the communications center, failing to isolate Hitler.