Karl Liebknecht and Rosa Luxemburg
During World War I Liebknecht became a leading figure in the development of opposition movements to the wartime government. He was the first in the Reichstag to vote against war credits and spoke out publicly, as early as January 1915, for the transformation of the national war into a civil or class war. The government conscripted him as a noncombatant but furloughed him to fulfill his duties as a deputy in the Reichstag and the Prussian Assembly. He served on the Düna sector of the Russian front, felling trees, peeling potatoes, and burying the rotting corpses of the dead, until he suffered physical collapse in October 1915. In 1916 he was expelled from the Social Democratic Party for opposing its leadership. The ouster brought him into close alliance with another revolutionary personality, Rosa Luxemburg. Together, they provided the leadership for illegal opposition to the war through the subversive Spartakusbund, which disseminated through its network of confidential underground agents various kinds of revolutionary propaganda. Liebknecht edited the famous illegal "Spartacus Letters," the "official" organ of the Spartakusbund.
On May 1, 1916, Liebknecht participated in a May Day demonstration in Berlin and called for the overthrow of the government and an end to the war and was tried and imprisoned. In October 1918 the climate in Germany had become more revolutionary and Liebknecht was granted an amnesty by the government of Prince Max of Baden.
Liebknecht entered the maelstrom of the German revolutionary period with great expectations. The Russian Soviet government celebrated his release from prison by a dinner for him at its embassy in Berlin. He planned to develop, through the Spartakusbund, a German revolution after the Soviet pattern. While the Social Democratic Party, under the leadership of Friedrich Ebert, channeled the revolution along moderate lines, Liebknecht harangued the masses to win support for a "real" revolution. He played a leading role in the formation of the German Communist Party, which attempted without success to organize the radical elements. A series of bloody clashes between the provisional government formed by Ebert after the downfall of the monarchy and the extreme radicals culminated in the January 1919 putsch in which Liebknecht resorted to force, a tactic both he and his father had strongly opposed. His use of force stimulated the growth of the counterrevolution, and both he and Rosa Luxemburg were among its first victims. On Jan. 15, 1919, they were shot to death by counterrevolutionary volunteers on the pretext of attempted escape while under arrest.
"Liebknecht, Karl" Encyclopædia Britannica Online.