After the First World War former senior officers in the German Army began raising private armies called Freikorps. These were used to defend the German borders against the possibility of invasion from the Red Army. Later they were used against attempts at revolution in Germany.
General Franz Epp led 30,000 soldiers to crush the Bavarian Socialist Republic in March, 1919. It is estimated that Epp's men killed over 600 communists and socialists over the next few weeks.
Herman Ehrhardt, a former naval commander and Wolfgang Kapp, a right-wing journalist, led a group of soldiers to take control of Berlin in March 1920. The Kapp Putsch was defeated by a general strike of trade unionists and Kapp was forced to flee to Sweden.
The Freikorps were dissolved in 1921 and later many of them joined Sturm Abteilung (Storm Section), the private army of Adolf Hitler.