Setting the scene
The Night of the Long Knives occurred June 30-July 2, 1934, when Adolf Hitler purged the leadership of the SA (Sturmabteilung), the Nazi paramilitary, and other opponents. The SA, led by Ernst Röhm, had 3 million members and demanded a 'second revolution' to replace the German army and implement socialist policies. The German army, business leaders, and President Hindenburg pressured Hitler to curb the SA. Hitler, seeing Röhm as a threat and needing army support to become president, decided to act.
What happened
On June 30, SS and Gestapo units arrested SA leaders across Germany. Röhm and dozens of SA officers were shot without trial. Hitler also used the purge to murder other enemies—former Chancellor Kurt von Schleicher, his wife, and Catholic politician Erich Klausener were killed. At least 85 people died, though estimates range to 200. The purge was justified as preventing a Röhm coup, a fabrication.
Why it still matters
The Night of the Long Knives secured Hitler's control. The SA was neutered, the SS under Himmler became dominant, and the army pledged loyalty to Hitler after Hindenburg's death a month later. The purge demonstrated Hitler's ruthlessness and that he would murder even loyal Nazis to consolidate power. It also showed German conservatives' willingness to accept murder for stability—the army and courts approved. The event marked the transition from Nazi movement to Nazi state, where terror became official policy.
Background
The Night of the Long Knives, also called the Röhm purge or Operation Hummingbird, was a purge that took place in Nazi Germany from 30 June to 2 July 1934. Chancellor Adolf Hitler, urged on by Hermann Göring and Heinrich Himmler, ordered a series of extrajudicial executions intended to consolidate his power and alleviate the German military's concerns about the role of Ernst Röhm and the Sturmabteilung (SA), the Nazis' paramilitary organization, known colloquially as "Brownshirts". Nazi propaganda presented the murders as a preventive measure against an alleged imminent coup by the SA under Röhm – the so-called Röhm Putsch. The SS gained ascendancy.