The Communist Party of Germany (Kommunistische Partei Deutschlands, kɔmuˈnɪstɪʃə paʁˈtaɪ ˈdɔʏtʃlants, KPD kaːpeːˈdeː) was a 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 West Germany during the postwar period until it was banned by the Federal Constitutional Court in 1956.
Founded in the aftermath of the First World War by socialists who had opposed the war, the party joined the Spartacist uprising of January 1919, which sought to establish a soviet republic in Germany. After the defeat of the uprising, and the murder of KPD leaders Rosa Luxemburg, Karl Liebknecht and Leo Jogiches, the party temporarily steered a more moderate, parliamentarian course under the leadership of Paul Levi. During the Weimar Republic period, the KPD usually polled between 10 and 15 percent of the vote and was represented in the national Reichstag and in state parliaments. Under the leadership of Ernst Thälmann from 1925 the party became thoroughly Stalinist and loyal to the leadership of the Soviet Union, and from 1928 it was largely controlled and funded by the Comintern in Moscow. Under Thälmann's leadership the party directed most of its attacks against the Social Democratic Party of Germany, which it regarded as its main adversary and referred to as "social fascists"; the KPD considered all other parties in the Weimar Republic to be "fascists".
The KPD was banned in the Weimar Republic one day after the Nazi Party emerged triumphant in the German elections in 1933. It maintained an underground organization in Nazi Germany, and the KPD and groups associated with it led the internal resistance to the Nazi regime, with a focus on distributing anti-Nazi literature. The KPD suffered heavy losses between 1933 and 1939, with 30,000 communists executed and 150,000 sent to Nazi concentration camps.