After several unsuccessful attempts by Stauffenberg to encounter Hitler, Göring and Himmler at the same time, he went ahead with the attempt at on 20 July 1944. Stauffenberg entered the briefing room carrying a briefcase containing two small bombs. The location had unexpectedly been changed from the subterranean to Albert Speer's wooden hut due to the heat on this summer's day. He left the room to arm the first bomb with specially adapted pliers. This was a difficult task for him as he had lost his right hand and had only three fingers on his left hand. A guard knocked and opened the door, urging him to hurry as the meeting was about to begin. As a result, Stauffenberg was able to arm only one of the bombs. He left the second bomb with his , Werner von Haeften, and returned to the briefing room, where he placed the briefcase under the conference table, as close as he could to Hitler. Some minutes later, he excused himself and left the room. After his exit, the briefcase was moved by Colonel Heinz Brandt.