The Night of the Long Knives, in June 1934, saw the wiping out of the SA's leadership and others who had angered Hitler in the recent past in Nazi Germany. After this date, the SS lead by Heinrich Himmler was to become far more powerful in Nazi Germany.
For all the power the Enabling Act gave Hitler, he still felt threatened by some in the Nazi Party. He was also worried that the regular army had not given an oath of allegiance. Hitler knew that the army hierarchy held him in disdain as he was 'only ' a corporal in their eyes. The Night of the Long Knives not only removed the SA leaders but also got Hitler the army's oath that he so needed.
By the summer of 1934, the SA's numbers had swollen to 2 million men. They were under the control of Ernst Röhm, a loyal follower of Hitler since the early days of the Nazi Party. The SA had given the Nazi's an iron fist with which to disrupt other political parties meetings before January 1933. The SA was also used to enforce law after Hitler became Chancellor in January 1933. To all intents, they were the enforcers of the Nazi Party and there is no evidence that Röhm was ever planning anything against Hitler.
By June 1934, the regular army hierarchy also saw the SA as a threat to their authority. The SA outnumbered the army by 1934 and Röhm had openly spoken about taking over the regular army by absorbing it into the SA. Such talk alarmed the army's leaders.
By the summer of 1934, Hitler had decided that Röhm was a 'threat' and he made a pact with the army. If Röhm and the other SA leaders were removed, the rank and file SA men would come under the control of the army but the army would have to swear an oath of loyalty to Hitler. The army agreed and Röhm's fate was sealed.
On the night of June 29th - June 30th 1934, units of the SS arrested the leaders of the SA and other political opponents. Men such as Gregor Strasser, von Schleicher and von Bredow were arrested and none of them had any connection with Röhm. The arrests carried on for 2 more nights.
Seventy seven men were executed on charges of treason though historians tend to think the figure is higher. The SA was brought to heel and placed under the command of the army. Hitler received an oath of allegiance from all those who served in the army. Röhm was shot. Others were bludgeoned to death.
The first the public officially knew about the event was on July 13th 1934, when Hitler told the Reichstag that met in the Kroll Opera House, Berlin, that for the duration of the arrests that he and he alone was the judge in Germany and that the SS carried out his orders. From that time on the SS became a feared force in Nazi Germany lead by Heinrich Himmler. The efficiency with which the SS had carried out its orders greatly impressed Hitler and Himmler was to acquire huge power within Nazi Germany.
before Wiessee, Hitler suddenly breaks his silence: "Kempka",
he says, "drive carefully when we come to the Hotel Hanselbauer.
You must drive up without making any noise. If you see a SA guard in
front of the hotel, don't wait for them to report to me; drive on and
stop at the hotel entrance." Then after a moment of deathly
silence: "Röhm wants to carry out a coup." An icy shiver ran
down my back. I could have believed anything, but not a coup by coup by
Kempka, Hitler's chauffeur.
Adolf Hitler, the German Chancellor, has saved his country. Swiftly and
with exorable severity, he has delivered Germany from men who had become
a danger to the unity of the German people and to the order of the
state. With lightening rapidity he has caused them to be removed from
high office, to be arrested, and put to death.
The names of the men who have been shot by his orders are already known. Hitler's love of Germany has triumphed over private friendships and fidelity to comrades who had stood shoulder to shoulder with him in the fight for Germany's future.
Daily Mail, July 2nd 1934.