The Sturmabteilung (SA; Storm Detachment; Brownshirts), founded in 1921, was the first paramilitary wing of the NSDAP; their initial assignment was to protect Nazi leaders at rallies and assemblies. They also took part in street battles against the forces of rival political parties and violent actions against Jews and others. Under Ernst Röhm's leadership the SA grew by 1934 to over half a million members—4.5 million including reserves—at a time when the regular army was still limited to 100,000 men by the Versailles Treaty.
Heinrich Himmler's Schutzstaffel (SS) took full control of the police and the concentration camps throughout Germany in 1934–35. Himmler expanded the role of the camps to hold so-called "racially undesirable elements", such as Jews, Gypsies/Romanis/Sintis, Serbs, Poles, disabled people, and criminals. The number of people in the camps, which had fallen to 7,500, grew again to 21,000 by the start of World War II and peaked at 715,000 in January 1945.