Why did Hitler kill Ernst Rohm?

That man was Ernst Rohm and in 1934 Hitler conspired to have him murdered. ... In 1918, as the war drew to its close, Rohm contracted Spanish Flu which killed millions across Europe. Rohm ... Rohm, along with Hitler, was arrested and charged with high treason, a charge that carried the death penalty. read more

Hitler then called Goering and Himmler and told them, "Buttercup," which was the agreed-upon code word that Roehm was dead. Goering and Himmler then rounded up the rest of the leaders of the Nazi left, e.g., Ernst Strasser, and murdered them in what became known as the Night of the Long Knives (it actually took 2-3 days). read more

Ernst Rohm was the leader of the SA, who could have actually challenged Hitler for leadership at some stage. He was also a leader of a more socialist faction within the party who was causing Hitler embarrassment with the industrialists that he had relied on for funding the party, and for rearming Germany. read more

Nevertheless, Hitler did name Röhm to the cabinet on 1 December as a minister without portfolio. Along with Gregor and Otto Strasser, Joseph Goebbels, Gottfried Feder, and Walther Darré, Röhm was a prominent member of the party's radical faction. read more