Stauffenberg along with his adjutant Werner von Haeftenem appeared in Wolf's Lair in the morning of July 20. Their plane from Berlin landed near headquarters at about 10.15. Stauffenberg announced that he wished to refresh himself and change his shirt. John von Freyend made his room available to him. Haeften came together with Stauffenberg to the designated area to help and prepare explosives.

Each explosive (made in England) had a single chemical starter working with a 10-minute delay. Getting detonators working turned out to be quite complex and lengthy. "It was necessary to first press copper scales which consisted of glass ampoules with acid. Acid had to destroy the wires in a specified time, tensioning spiral feathers with starter pins. It had to be done very carefully in order not to press the tensioning wires. Then checking whether the detonators were still tight was done through a hole and then the fuse was removed and the starter inserted."

A few minutes before 12.30 Stauffenberg went to the barrack for the meeting. On the way John von Freyend offered to help Stauffenberg carry the briefcase, but the colonel refused. However, just in front of the barrack he passed the briefcase to him, wanting it to be as near Hitler as possible. They came to the barrack when the General Heusinger was discussing the situation on the Eastern Front. John von Freyend asked Admiral Voss to move to other side of the table to make place for Stauffenberg. The briefcase with explosives was placed outside the right bracket table at a distance of about 2.5 - 3 meters from Hitler. After several minutes had passed Stauffenberg announced that he had to make a phone call. The phones were in a neighbouring room. His adjutant went with him. At the time when Stauffenberg and his adjutant got into the car the explosion shook the ground.

Driving near the barrack they saw clouds of smoke, charred papers rotating in the air, injured and running people. They managed to leave the zone without difficulty: the car's passenger was a widely recognized person - his military career, wounds from Africa and position made him highly respected. At 13.15 they flew away back to Berlin. Stauffenberg and Haeften landed in Berlin convinced of the success of their mission. Gen. Olbricht announced the launch of the operation "Valkyrie". The putsch attempt lasted approximately 7 hours and collapsed at midnight. Count Claus von Stauffenberg was arrested and sentenced to death the same night at about 0.30 . He was executed immediately.

Explosives planted by Colonel Stauffenberg destroyed the interior meeting hall. There were broken chairs, glass and papers everywhere and only a small piece of the solid oak table remained. There was a hole in the ground about 1.5 m in diameter on the spot where the bomb was placed.

At the time of explosion there were 24 people in the room. Hitler stood in the middle of the table's length, turned to face the three open windows on the shorter barrack wall. He was leaning on the table with his head on his hands.

The participants of the meeting described the explosion as a powerful blow of air, accompanied by loud noise and flames. Almost everyone was thrown on the floor by the impact, but no one was thrown through the window as some studies indicate. Suddenly someone cried: "Where is the Führer?" -- it was Keitel. After several seconds he found Hitler and helped him leave the premises.

Prof. von Hasselbach put on the first bandages and then prof. Morell took over Hitler. The Führer’s right elbow was bleeding, but the arm functioned normally. His skin was slightly scratched on the left hand. No serious damage of the hearing organ was detected apart from the breaking of the eardrum. Führer was clearly excited. He said that he had been aware for a long time that there were traitors surrounding him. Three hours after the attack Hitler was already able to welcome Mussolini at the local railway station (the visit of the Italian leader in Wolf's Lair lasted only 2.5 hours).

As a result of the explosion the stenografer and three generals were mortally wounded. The majority of participants had to be treated in hospital due to injuries such as broken eardrums or brain shock. Professor von Hasselbach looked after the patients.

"The experts researching the effects of bomb explosions agreed with the fact that the quantity of the explosive brought by Stauffenberg to the meeting would have killed all participants if it had been held in the concrete bunker. Because the meeting was held in a barrack, injuries were relatively small " (14, p. 476).

On July 21 at about 1.00 A.M. a night radio broadcast Hitler's speech : "... German companions, I don't know how many times already someone planned and made an attempt to kill me. If today I speak to you, I do it for two reasons: First, I want you to hear my voice to let you know that I'm alive and healthy. Secondly, I want you to learn more about the crime, which has nothing equal in the history of Germany. A small group of selfish, devoid of conscience and at same time murderous, foolish officers planned a plot to remove me together with my military command. The bomb planted by Colonel Count von Stauffenberg exploded 2 meters from my right hand... I survived entirely without damage except for minor scratches, bruises and burns. I accept this as a confirmation of my tasks commissioned by Providence to continue to pursue my goal in life as I did until now. The group of people represented by those traitors has nothing in common with Wermacht or the German Army. This time we are going to make even in the National Socialists’ style! " (7, p. 324).

The rest of the speech was a mixture of vulgar insults ended with the announcement that traitors will be mercilessly removed.

To investigate the events and detect further conspirators Himmler set up a "special committee” on July 20, The Protocols of the results were directed to Himmler, who in turn submitted them to Hitler or other Nazi leaders. About 700 people were arrested in all. Approximately 180 people were killed - 89 of them in Plötzensee.