The Communist Party of Germany was the major far-left political party in the Weimar Republic during the interwar period, an underground resistance movement in Nazi Germany, and a minor party in Allied-occupied Germany and West Germany during the post-war period until it merged with the SPD in the Soviet occupation zone in 1946 and was banned by the West German Federal Constitutional Court in 1956.
The construction of the KPD began in the aftermath of the First World War by Rosa Luxemburg's and Karl Liebknecht's faction of the Independent Social Democratic Party of Germany (USPD) who had opposed the war and the Majority Social Democratic Party of Germany (MSPD)'s support of it.
The KPD joined the Spartacist uprising of January 1919, which sought to establish a council republic in Germany.