Red Ruhr Army was an army of 50 000 left wing workers, formed on March 13, 1920 as a reaction to the Kapp Putsch in the Ruhr Valley, the richest industrial area of Germany. After calling a general strike on March 14, the Red Ruhr Army defeated the Freikorps and regular army units in the area and started the biggest armed workers' uprising in Germany, also called Märzrevolution (March Revolution).

While the bourgeoisie feared a left wing putsch, 300,000 mine workers supported the "Red - Ruhr army". The strikers conquered Düsseldorf, Eberfeld, Essen and soon had control over the whole Ruhr area.

After the failure of negotiations with the strikers the government sent more troops into the Ruhr area on April 2, 1920, which caused civil-war like circumstances. These government troops consisted of regular government troops but also of Freikorps men who finally smashed the workers' uprising and reconquered the Ruhr area. While the Free Corps only lost 250 men the Red Ruhr Army lost 1000 men during the bitter fights.

Finally, on April,12 Reichswehr General von Watter banned any illegal behavior of his troops which put an end to all battles and fights in the Ruhr area.

Between 1919 and 1922 there were 356 political murders in Germany. Walther Rathenau, Germany's Foreign Minister, was murdered as part of the escalating violence.