The Communist Party of Germany (in German, Kommunistische Partei Deutschlands – KPD) was formed in December of 1918 from the Spartacist League, which originated as a small factional grouping within the Social Democratic Party (SPD) opposed to the First World War on the grounds that it was an imperialist war in which the working class had no interest. The faction was led by Rosa Luxemburg and Karl Liebknecht. During the Nazi period, the KPD was brutally suppressed, and known sympathizers were sent to concentration camps as a part of the Holocaust. After World War II, the Soviet occupation authority forced the KPD and SPD organizations in their sphere of influence to merge into the Socialist Unity Party of Germany (SED), which they installed as the government of East Germany. Following German reunification, the SED became the Party of Democratic Socialism (PDS), which is still a force in German politics today, especially in the east.

Early period

Technically, its first incarnation was as the Internationale, based on a journal of that name which was swiftly suppressed by the authorities. The faction became known as the Spartacus League after a series of letters written by Luxemburg, its preeminent theoretician, which she signed "Spartacus".

When the tide of popularity turned against the war, sections of the SPD turned leftwards and broke away to form the Independent Social Democratic Party of Germany (USPD). The Spartacus League joined the new party as an autonomous faction. However, a debate was underway as to whether a new Communist party should be formed in Germany that would ally itself with the Bolsheviks in Russia. As well as the Spartacus League, the International Communists of Germany (IKD), who had their theoretical point of origin in the pre-war Left Radical tendency, were to take part in the foundation of the Communist Party.

The party was first led by Rosa Luxemburg and Karl Liebknecht, though large portions of the membership opposed their views. Some even formed a splinter organization, the Communist Workers Party. The failed Spartacist Uprising in Berlin was carried out one month after the KPD's formation, in January of 1919, against the specific instructions of Luxemburg and Liebknecht. The right wing Freikorps militias joined with the remnants of the German army and the Social Democrats to suppress the revolt. Liebknecht and Luxemburg were captured, tortured, killed, and dumped into a canal.

This left the party in the hands of Karl Levi, who sought to win over social democratic workers. These efforts were rewarded when a substantial section of the Independent Social Democratic Party joined the KPD, making it a mass party for the first time.

Other prominent members included Leo Jogiches, Clara Zetkin, Paul Levi, Franz Mehring and Ernst Meyer.

Stalinism

However, the leadership was never stable and Levi was expelled by the Comintern for indiscipline, despite Lenin's argument that his position was correct. Further leadership changes took place in the early 1920s, and a splinter group (Communist Party Opposition) was set up under the leadership of Heinrich Brandler and August Thalheimer, who had been expelled. After 1923, a leadership was installed loyal to the rising Stalin faction in Russia. In 1928, this leadership, headed by Ernst Thälmann, supported the so called Third Period conception that the Social Democrats were a greater enemy than the National Socialists or Nazis.

In the Weimar republic era, the KPD pursued (on direction from Moscow) the disastrous policy of concentrating on the Social Democrats first, assuming that this would lead to a Nazi regime that would soon collapse and be replaced with socialism. During this period, they maintained a solid electoral performance, gaining 100 deputies in the November 1932 elections. In the presidential election in 1932, Thälmann took 13.2% of the vote, compared to 30.1% that Hitler got.

The Nazi era

Soon after the appointment of Hitler as Chancellor, the Reichstag was set on fire. The Nazis publicly blamed the fire on Communist agitators (though many historians believe that the Nazis themselves set the fire). They used the fire as a pretext to introduce laws enabling suppression of political parties. The Enabling Act, which legally gave Hitler dictatorial control of Germany, was passed by a Reichstag session held after the Communist deputies had been arrested and jailed.

The KPD was brutally suppressed by the Nazis – known Communists were sent to concentration camps and systematically killed during the Holocaust. Many German Communists ended up dead (Ernst Thälmann, Werner Seelenbinder), in exile (Walter Ulbricht), or were imprisoned (Erich Honecker).

Post-World War II

In East Germany

After World War II, Soviet occupation authorities forced the KPD to merge with the Social Democrats into the Socialist Unity Party (German Sozialistiche Einheitspartei Deutschlands, or SED), which became the sole governing power in East Germany.

After German reunification, the SED became the Party of Democratic Socialism (PDS), which is still influential. As of 2004, Berlin is governed by a PDS/SPD coalition.

In West Germany

In West Germany, the party was banned in 1956 by the Federal Constitutional Court of Germany. It was later legalised as the German Communist Party (DKP), which still exists.

In West Berlin, members were reorganized into the Socialist Unity Party of West Berlin (German: Sozialistiche Einheitspartei Westberlins) after the war. During the Cold War, SEW functioned as separate organization from the West German DKP and disappeared after the reunification of Germany, largely merging into the PDS.

Since 1990

In 1990, a new KPD was founded in East Germany after the SED had transformed itself into the PDS. The new KPD declared itself to be a Bolshevist party in 1999 and today has its own youth organisation (KJVD, Kommunistischer Jugendverband Deutschlands/Communist youth association of Germany) and a newspaper called Die rote Fahne ("The Red Flag"). The party lacks influence at both the federal and state level.