Adolf Hitler was in a furious temper when his flight touched down in Munich at 4.30am on 30 June 1934. He was not only seething, he was also alarmed, desperate for the latest news about the trouble in the city. Before he’d flown out of Essen, almost three hours earlier, Hitler had been informed that the Brownshirts were out on the streets causing mayhem.

Hitler was met off the plane by a Nazi Party leader, who told him that 3,000 Sturmabteilung (SA) stormtroopers, the party’s brownshirted paramilitary wing, had rampaged through Munich, smashing windows and shouting slogans, many of which accused Hitler of ‘treachery’.

The Nazi leader shook with rage on what he called the “blackest day of my life”. If there was any treachery afoot then it came from Ernst Röhm, the SA’s chief of staff. Adolf Hitler tore up the day’s itinerary. There would be no conference with Röhm and the other leaders of the SA as scheduled. The time for talking had passed.

He ordered his driver to race to the Bavarian Ministry of the Interior, and once there he summoned two senior SA figures. When they arrived, Hitler physically stripped them of their rank badges, screaming as he did so: “You are under arrest and will be shot!”

Hitler next assembled a party of armed detectives and SS bodyguards and, in a convoy of saloon cars, set off to the Hotel Hanselbauer in Bad Wiessee, a spa town 32 miles south of Munich. Only the hotel staff were up and about when Hitler marched through the front door and demanded the number of Röhm’s room. He bounded up the stairs to the first floor with two detectives at his heels and burst in. “You’re under arrest!” he roared. A hungover Röhm seemed unperturbed by the angry intrusion. “Hail, my leader,” he muttered, looking up from his pillow.

By the time Röhm emerged from his room – wearing a blue suit and smoking a cigar – the rest of the SA officers at the hotel had been locked in a linen cupboard. Hitler had already issued instructions that they were to be shot. But what to do about Röhm? That was the question that troubled Hitler as he returned to Munich.