b. Aug. 13, 1871, Leipzig
German Social Democrat, who, with Rosa Luxemburg and other radicals, founded the Spartakusbund (Spartacus League), a Berlin underground group that became the Communist Party of Germany, dedicated to a socialist revolution. Liebknecht was killed in the Spartacus Revolt of January 1919.
The son of Wilhelm Liebknecht, Karl grew up during the years when the Anti-Socialist Law was in force against his father's Socialist Labour Party (which became the Social Democratic Party in 1891). With financial help from the party, he studied law and political economy, first at Leipzig and then at Berlin, where he earned his doctor's degree. He planned to devote his career to the defense of Marxism.
After serving with the Imperial Pioneer Guards in Potsdam during 1893-94 and subsequently as a junior barrister in Westphalia, he returned to Berlin in 1898. In 1900, the year of his father's death, he married his first wife, Julie Paradies, by whom he had three children. She died 10 years later, and in 1912 he married Sophia Ryss, a woman of Russian birth who had graduated from the University of Heidelberg.
In 1904, at a trial at Königsberg (now Kaliningrad, Russia), he defended propertyless peasants accused of infiltrating socialist propaganda from East Prussia into tsarist Russia. His defense of the accused was primarily an apology for social democracy and provided him with a platform for his attacks against militarism. In 1907 he played a principal role in the establishment of the International Union of Socialist Youth Organizations in Stuttgart. His publication of Militarismus und Antimilitarismus in the same year earned him a jail sentence of 18 months in Glatz, Silesia. While still in prison, he won a seat in the Prussian Landtag, and in 1912 he entered the Reichstag as the chief spokesman against the government and against the growing movement within the Social Democratic Party to revise its Marxist doctrine.
"Liebknecht, Karl" Encyclopædia Britannica Online.