The Sturmabteilung (German: "Assault Division"; abbreviated as SA), were a paramilitary organization within the Nazi Party in interwar Germany, originally founded to protect Nazi meetings from disruption, they were the tool used to intimidate, threaten, and commit acts of violence against political opponents as well as Jews and other individuals opposed by party doctrines. Commonly referred to as the "Brownshirts" or "Storm troopers", the SA at its height numbered greater than twenty times that of the German Army.
The origins of the SA naturally followed the beginnings of the Nazi Party. At the end of the First World War the party was a small group founded by a locksmith named Anton Drexler in 1918, merging with another group in 1919 under the name "German Workers' Party" (Deutsche Arbeiterpartei or DAP). An obscure former corporal in the regular army, Adolf Hitler, joined the DAP in September 1919, and through his fiery oratory would transform the small party into the "National Socialist German Workers Party" (Nationalsozialistische Deutsche Arbeiterpartei or NSDAP). When the party expanded, a force was needed to protect meetings, and the SA was created in Munich in 1921, organized first to kick out hecklers at Nazi meetings, then to break up the meetings of other parties. The fascists of Italy under Benito Mussolini would inspire a uniform choice: brown shirts worn by all members, emblazoned with a red band bearing a swastika on the left arm. The SA was a group consisting largely of ex-soldiers, Freikorps (Free Corps) members, and common thugs who believed in the Nazi cause; they would march in Nazi rallies, assault political opponents, and intimidate voters during elections. Hitler used them unsuccessfully during the failed Beer Hall Putch in Munich, 1923, which resulted in a temporary disarray.
Still believing in Hitler's cause, the SA reorganized by 1925. In 1931, they were led by a radical who had grandiose dreams of his own: Ernst Röhm. An anti-capitalist who believed in a permanent, continuing revolution, Röhm would use the SA to propel Hitler to the chancellery as well as increase the size of the organization to such an extent that it would threaten to replace the much smaller 100,000 man army as Germany's main fighting force, with himself at its head. To that extent the charismatic Röhm swelled the SA from approximately 200,000 in 1931 to close to 2 million men by 1933.
To consolidate power, Hitler needed the backing of two groups considered fundamental to Germany's well-being: the big-business industrialists - such as I.G. Farben and Krupp - and the army. Both eyed the SA as an uncontrolled mob, and Röhm as a power-seeker; indeed, evidence that he was an avid homosexual only added fuel to the fire. The powerful men in the Nazi hierarchy - Heinrich Himmler, Hermann Göring, and Joseph Goebbels - saw Röhm and the SA as a threat to their recently-won acquisition of power and decided on a plan to eliminate him.
Beginning on June 30 1934, the Night of the Long Knives (die Nacht der langen Messer) took place near Munich at the Hanselbauer Hotel in Bad Wiessee where it was known that SA leadership were on holiday; the plan for execution was conceived by Himmler and Reinhard Heydrich. Röhm - caught in bed with a male SA lover by Hitler himself - was summarily executed, as well as many SA leaders over the next two days. Himmler gained enormously from the killings; his Schutzstaffel (SS) became its own separate branch and would later grow from Hitler's personal bodyguard to become a terrifying force in World War II. Its leadership decimated, the SA became a shadow of its former self. Thereafter, its only military use was that of training units for the German armed forces and later acting as the Home Guard during World War II.
The term is sometimes erroneously broadened to include all Nazis and even all fascists, although strictly speaking Italian fascists were Blackshirts, for similar reasons of their uniform.  The term was used earlier by the German Army to denote special trench assault units during World War I.
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