Karl Liebknecht (1871 - 1919) was a radical social democrat and head of the Spartakusbund (together with Rosa Luxemburg). The Spartakusbund was a radical social movement with plans to overthrow the government. It was the basis of the communist party of Germany (KPD). Liebknecht was arrested and murdered by Freikorps troops in Berlin in 1919.
Rosa Luxemburg (1870 - 1919) was a socialist politician, an advocate of social revolution and head of the Spartakusbund (together with Karl Liebknecht). She wrote "die Akkumulation des Kapitals" (1913) and "Das Kommunistische Manifest" in 1918. She was arrested and murdered by Freikorpstroups in Berlin in 1919.