Stauffenberg sat in the conference room and hoped nobody noticed the sweat clinging to his face, his shirt, his shaking hand. The talk went over his head and he mumbled an excuse to change his shirt in Wilhelm Keitel’s office. Fumbling only a little, he pulled out a pair of pliers and crushed the end of a pencil detonator inserted into a 1 kg block of plastic explosive wrapped in brown paper.
The detonator consisted of a thin copper tube containing acid that would take ten minutes to silently eat through wire holding back the firing pin from the percussion cap. He then placed the primed bomb quickly inside his briefcase, adding another. Someone entered and said that he was needed. He returned to the conference room with a smile.
Trying not to laugh as Major Ernst John von Freyend helped him put his briefcase under the table around which Hitler and more than 20 officers had gathered, he left the room again, the excuse of a phone call guiding him.Colonel Heinz Brandt also left the room.