Karl Paul August Friedrich Liebknecht was a German socialist and anti-militarist. A member of the Social Democratic Party of Germany (SPD) beginning in 1900, he was one of its deputies in the Reichstag from 1912 to 1916, where he represented the left-revolutionary wing of the party. In 1916 he was expelled from the SPD's parliamentary group for his opposition to the Burgfriedenspolitik, the political truce between all parties in the Reichstag while the war lasted. He twice spent time in prison, first for writing an anti-militarism pamphlet in 1907 and then for his role in a 1916 antiwar demonstration. He was released from the second under a general amnesty three weeks before the end of the First World War.

The Spartacist uprising, also known as the January uprising, was an armed uprising that took place in Berlin from 5 to 12 January 1919. It occurred in connection with the November Revolution that broke out following Germany's defeat in World War I. The uprising was primarily a power struggle between the Social Democratic Party of Germany (SPD) led by Friedrich Ebert, which favored a social democracy, and the Communist Party of Germany (KPD), led by Karl Liebknecht and Rosa Luxemburg, which wanted to set up a council republic similar to the one established by the Bolsheviks in Russia. In 1914 Liebknecht and Luxemburg had founded the Marxist Spartacus League, which gave the uprising its popular name.