The Freikorps Oberland was a voluntary paramilitary organization that, in the early years of the Weimar Republic, fought against communist and Polish insurgents. It was successful in the 1921 Battle of Annaberg and became the core of the Sturmabteilung (SA) in Bavaria while several members later turned against the Nazis.

The Battle of (the) Annaberg was the biggest battle of the Silesian Uprisings. The battle, which took place between May 21–26, 1921, was fought at the Annaberg, a strategic hill near the village of Annaberg O.S., located southeast of Oppeln (Opole) in Upper Silesia, Weimar Germany. After the hill had been captured by irregular Polish-Silesian units in the Third Silesian Uprising, German Freikorps pushed the Polish forces back. The final border was determined by political and diplomatic efforts.