The League subsequently renamed itself the Kommunistische Partei Deutschlands (KPD), joining the Comintern in 1919. The League and the subsequent KPD were famous for pitched street battles with police and other direct action militant activities, some of which Vladimir Lenin disapproved of as premature, anarchistic, misguided, etc. In January 1919, the KPD along with the independent socialist USPD staged massive street demonstrations in protest of a swerve to the right by the Weimar government (then led by the autocratic right-wing of the SPD under Chancellor Friedrich Ebert). In response, the government claimed that the opposition was planning a general strike and communist revolution in Berlin. The government then deputized the proto-fascist freikorps to kill the opposition leaders even though it was well-known that Luxemburg and Liebknecht were both opposed to any revolution at that time. The "uprising" was quickly crushed by the government of the Weimar Republic; however, the government's reliance on the proto-fascist freikorps in place of the army or police paved the way for a putsch by that organization and, in the long run, for the rise of the Nazis (many of whom, including Ernst Röhm, the founder of the Nazi Sturmabteilung, were former freikorps).
After the Russian Revolution of 1917, the Spartacists decided to agitate for a similar course, a government based on local workers' councils (soviets), in Germany. Liebknecht and Luxemburg were imprisoned from 1916 until 1918 for their roles in helping to organize a public demonstration in Berlin against German involvement in the war. After the November revolution which overthrew the Kaiser at the end of World War I, a period of instability and revolutions began, which would last until 1923. Liebknecht declared a socialist republic in Germany from a balcony of the Kaiser's Berliner Stadtschloss in November 1918 — the same night that Philipp Scheidemann of the SPD declared the Weimar Republic from the Reichstag.
In December 1918, the Spartakusbund became the Communist Party of Germany (KPD). Although it has long been claimed that January 1, 1919, the KPD attempted to take control of Berlin in what came to be known as the Spartakus uprising, this did not in fact occur as Luxemburg,Liebknecht and others had successfully argued that an uprising would be premature since the Spartakusbund was too weak and not enough of the working class had come over to its side. It would be more accurate to say that the Communists and Independent Socialists launched a series of protests which the authoritarian socialists responded to by violently suppressing opposition on the orders of chancellor Friedrich Ebert. Luxemburg and Liebknecht, among many others, were murdered while held prisoner by the Freikorps, and their bodies dumped in a river. Hundreds of Spartacists were killed in the weeks following the uprising.
One of the most notable parts of the Spartacist Manifesto (published in 1918) is the following: