• Political Theorist and Philosopher Rosa Luxemburg, 1871
• Marxist Politician Karl Liebknecht, 1871

 

In 1915, after the SPD supported German involvement in World War I, she and Karl Liebknecht co-founded the anti - war Spartakusbund (Spartacist League) which eventually became the Communist Party of Germany (KPD). During the German Revolution she founded the Die Rote Fahne (The Red Flag), the central organ of the Spartacist movement.

She regarded the Spartacist uprising as a blunder, but supported it after Liebknecht ordered it without her knowledge. When the revolt was crushed by the social democratic government and the Freikorps (World War I veterans who banded together into right wing paramilitary groups), Luxemburg, Liebknecht and some of their supporters were captured and murdered. Luxemburg was shot and her body thrown in the Landwehr Canal in Berlin. After their deaths, Luxemburg and Karl Liebknecht became martyrs for Marxists. According to the Federal Office for the Protection of the Constitution, commemoration of Rosa Luxemburg and Karl Liebknecht continues to play an important role among the German far left.

Luxemburg was born to a Jewish family in Zamość on 5 March 1871, in Russian controlled Congress Poland. She was the fifth child of timber trader Eliasz Luxemburg and Line Löwenstein. After being bedridden with a hip ailment at the age of five, she was left with a permanent limp.

On her family's moving to Warsaw, Luxemburg attended a Gymnasium from 1880. From 1886 onward, she belonged to the Polish, left wing Proletariat party (founded in 1882, anticipating the Russian parties by twenty years). She began in politics by organizing a general strike; this resulted in four of its leaders being put to death and the party being disbanded, though remaining members, Luxemburg among them, met in secret. In 1887, she passed her Matura examinations. After fleeing to Switzerland to escape detention in 1889, she attended Zürich University (as did the socialists Anatoli Lunacharsky and Leo Jogiches), studying philosophy, history, politics, economics and mathematics. She specialized in Staatswissenschaft (the science of forms of state), the Middle Ages and economic and stock exchange crises.

In 1893, with Leo Jogiches and Julian Marchlewski (alias Julius Karski), Luxemburg founded the newspaper Sprawa Robotnicza ("The Workers' Cause"), to oppose the nationalist policies of the Polish Socialist Party, believing that only through socialist revolution in Germany, Austria and Russia could an independent Poland exist. She maintained that the struggle should be against capitalism, and not just for an independent Poland. Her position denying a national right of self determination under socialism provoked philosophical tension with Vladimir Lenin. She and Leo Jogiches co-founded the Social Democratic Party of the Kingdom of Poland (SDKP) (later Social Democracy of the Kingdom of Poland and Lithuania [SDKPiL) by merging with Lithuania's social democratic organization. Despite living in Germany for most of her adult life, Luxemburg was the principal theoretician of the Polish Social Democrats, and led the party in a partnership with Jogiches, its principal organizer.

The recently published Letters of Rosa Luxemburg shed important light on Rosa Luxemburg’s life in Germany. As Irene Gammel writes in a review of the English translation of the book in the Globe and Mail: “The three decades covered by the 230 letters in this collection provide the context for her major contributions as a political activist, feminist and writer. In her controversial tome of 1913, The Accumulation of Capital, as well as through her work as a co-founder of the radical Spartacus League, Luxemburg helped to shape Germany’s young democracy by advancing an international, rather than a nationalist, outlook. This farsightedness partly explains her remarkable popularity as a socialist icon and its continued resonance in movies, novels and memorials dedicated to her life and oeuvre.” Gammel also notes that for Rosa, “the revolution was a way of life,” and yet that the letters also challenge the stereotype of “Red Rosa” as a stupid fighter.

In 1898 Luxemburg married Gustav Lübeck, obtained German citizenship, and moved to Berlin. There, she was active in the left wing of the Social Democratic Party of Germany (SPD), in which she sharply defined the border between her faction and the Revisionism Theory of Eduard Bernstein by attacking him in an 1899 brochure titled Social Reform or Revolution. Luxemburg's rhetorical skill made her a leading spokeswoman in denouncing the SPD's reformist parliamentary course. She argued that the critical difference between capital and labor could only be countered if the proletariat assumed power and effected revolutionary changes in production methods. She wanted the Revisionists ousted from the SPD. That did not occur, but Karl Kautsky's leadership retained a Marxist influence on its program.

From 1900 Luxemburg published analyses of contemporary European socio - economic problems in newspapers. Foreseeing war, she vigorously attacked what she saw as German militarism and imperialism. She wanted a general strike to rouse the workers to solidarity and prevent the coming war; the SPD leaders refused, and she broke with Karl Kautsky in 1910. Between 1904 and 1906 she was imprisoned for her political activities on three occasions. In 1907, she went to the Russian Social Democrats' Fifth Party Day in London, where she met Vladimir Lenin. At the Second International (Socialist) Congress, in Stuttgart, she moved a resolution, which was accepted, that all European workers' parties should unite in attempting to stop the war.

Luxemburg taught Marxism and economics at the SPD's Berlin training center. A student of hers, Friedrich Ebert later became SPD leader, and later the Weimar Republic's first president. In 1912 she was the SPD representative at the European Socialists congresses. With French socialist Jean Jaurès, she argued that European workers' parties should organize a general strike when war broke out. In 1913 she told a large meeting: "If they think we are going to lift the weapons of murder against our French and other brethren, then we shall shout: 'We will not do it!'" But in 1914, when nationalist crises in the Balkans erupted to violence and then war, there was no general strike and the SPD majority supported the war – as did the French Socialists. The Reichstag unanimously agreed to financing the war. The SPD voted in favor of that and agreed to a truce (Burgfrieden) with the Imperial government, promising to refrain from any strikes during the war. This led Luxemburg to contemplate suicide: The "revisionism" she had fought since 1899 had triumphed.

In response Luxemburg organized anti - war demonstrations in Frankfurt, calling for conscientious objection to military conscription and the refusal to obey orders. On that account, she was imprisoned for a year for "inciting to disobedience against the authorities' law and order".

In August 1914 Luxemburg, along with Karl Liebknecht, Clara Zetkin and Franz Mehring, founded the Die Internationale group; it became the Spartacus League in January 1916. They wrote illegal, anti - war pamphlets pseudonymously signed "Spartacus" (after the slave - liberating Thracian gladiator who opposed the Romans); Luxemburg's pseudonym was "Junius" (after Lucius Junius Brutus, founder of the Roman Republic).

The Spartacist League vehemently rejected the SPD's support for the war, trying to lead Germany's proletariat to an anti - war general strike. As a result, in June 1916 Luxemburg was imprisoned for two and a half years, as was Karl Liebknecht. During imprisonment, she was twice relocated, first to Posen (now Poznań), then to Breslau (now Wrocław).

Friends smuggled out and illegally published her articles. Among them was "The Russian Revolution", criticizing the Bolsheviks, presciently warning of their dictatorship. Nonetheless, she continued calling for a "dictatorship of the proletariat", albeit not the One Party Bolshevik model. In that context, she wrote "Freiheit ist immer die Freiheit des Andersdenkenden" ("Freedom is always the freedom of the one who thinks differently"). Another article, written in 1915 and published in June 1916, was "Die Krise der Sozialdemokratie" ("The Crisis of Social Democracy").

In 1917 the Spartacist League was affiliated with the Independent Social Democratic Party (USPD) (anti - war, ex - SPD members, founded by Hugo Haase). In November 1918 the USPD and the SPD assumed power in the new republic upon the Kaiser's abdication. This followed the German Revolution begun in Kiel, when Workers' and Soldiers' Councils seized most of Germany, to put an end to World War I and to the monarchy. The USPD and most of the SPD members supported the councils, while the SPD leaders feared, they could found a Räterepublik ("Council Republic"), in emulation of the system of Soviets of the Russian revolutions of 1905 and 1917.

Luxemburg was freed from prison in Breslau on 8 November 1918. One day later Karl Liebknecht, who had also been freed from prison, proclaimed the Freie Sozialistische Republik (Free Socialist Republic) in Berlin. He and Luxemburg reorganized the Spartacus League and founded the Red Flag newspaper, demanding amnesty for all political prisoners and the abolition of capital punishment. On 14 December 1918 they published the new program of the Spartacist League.

From 29 – 31 December 1918, they took part in a joint congress of the Spartacist League, independent Socialists, and the International Communists of Germany (IKD), that led to the foundation of the Communist Party of Germany (KPD) under the leadership of Karl Liebknecht and Luxemburg on 1 January 1919. She supported the new KPD's participation in the Weimar National Assembly that founded the Weimar Republic; but she was outvoted.

In January 1919 a second revolutionary wave swept Berlin. Unlike Liebknecht, Luxemburg rejected this violent attempt to seize power. But the Red Flag encouraged the rebels to occupy the editorial offices of the liberal press.

In response to the uprising, Social Democratic leader Friedrich Ebert ordered the Freikorps to destroy the left wing revolution. Luxemburg and Liebknecht were captured in Berlin on 15 January 1919 by the Freikorps' Garde - Kavallerie - Schützendivision. Its commander, Captain Waldemar Pabst (1880 – 1970), along with Lieutenant Horst von Pflugk - Harttung (1889 - 1967), questioned them violently and then gave the order to execute them. Luxemburg was knocked down with a rifle butt by soldier Otto Runge (1875 – 1945), then shot in the head, either by Lieutenant Kurt Vogel (1889 - 1967) or Lieutenant Hermann Souchon (1894 – 1982); her body was flung into Berlin's Landwehr Canal. In the Tiergarten Karl Liebknecht was shot and his body, without a name, brought to a morgue.

After the murders, a new series of violent outrages in Berlin and whole Germany started, with thousands of KPD members, other revolutionaries and civilians being killed. Finally Workers' and Soldiers' councils and the People's Navy Division (Volksmarinedivision), who had positioned themselves to the left side meanwhile, disbanded.

The German revolution went to its terminal phase, with numbers of armed outrages and strikes all over Germany up to May 1919, including Berlin, Bremen Soviet Republik, Saxony, Saxony Gotha, Hamburg, the Rhinelands and the Ruhr region. Last to stand was the Munich Soviet Republic until 2 May 1919.

More than four months after the murders, on 1 June 1919 Luxemburg's corpse was found and identified after an autopsy at the Berlin Charité hospital.

Otto Runge was sentenced to two years imprisonment (for "attempted manslaughter") and Lieutenant Vogel to four months (for failing to report a corpse). However, the latter escaped after a brief period in custody while Pabst and Souchon went unpunished. The Nazis later compensated Runge for having been jailed (he died in Berlin in Soviet custody after the end of World War II), and they merged the Garde - Kavallerie - Schutzendivision into the SA. In an interview given to the German news magazine "Der Spiegel" in 1962 and again in his memoirs, Pabst maintained that two SPD leaders, defense minister Gustav Noske and chancellor Friedrich Ebert, had approved of his actions. This statement has never been confirmed, since neither parliament nor the courts examined the case.

Luxemburg and Liebknecht were buried at Friedrichsfelde Central Cemetery in Berlin, where socialists and communists commemorate them every year, on the second Sunday of January.

On 29 May 2009 Spiegel online, the internet branch of news magazine Der Spiegel, reported the possibility that someone else's remains had mistakenly been identified as Luxemburg's and buried as hers.

Forensic pathologist Michael Tsokos, head of the Institute of Legal Medicine and Forensic Sciences at the Berlin Charité, had recently discovered a preserved corpse lacking head, feet, or hands, in the cellar of the Charité's medical history museum. He considered the corpse's autopsy report suspicious and decided to perform computer tomography on the remains. The body showed signs of having been waterlogged at some point, and CT scans showed that it was the body of a woman of 40 – 50 years of age who suffered from osteoarthritis and had legs of differing length. At the time of her murder Rosa Luxemburg was 47 years old, and furthermore suffered from a congenital dislocation of the hip which resulted in her legs being of different lengths. A laboratory in Kiel also tested the corpse using carbon dating techniques and confirmed that it dated from the same period as Luxemburg's murder.

The original autopsy performed on 13 June 1919 on the body that was eventually buried at Friedrichsfelde showed certain inconsistencies which supported Tsokos' hypothesis. The autopsy explicitly noted an absence of hip damage, and stated that there was no evidence that the legs were of different lengths. Additionally, the autopsy showed no traces on the upper skull of the two blows by rifle butt inflicted upon Luxemburg. Finally, while the 1919 examiners noted a hole in the corpse's head between left eye and ear, they did not find an exit wound or the presence of a bullet within the skull.

Assistant pathologist Paul Fraenckel appeared to have had doubts at the time that the corpse he had examined was that of Rosa Luxemburg, and in a signed addendum distanced himself from his colleague's conclusions; it was this addendum and the inconsistencies between the autopsy report and the known facts that persuaded Tsokos to examine the remains more closely. As regards the missing hands and feet, according to eyewitnesses, when Luxemburg's body was thrown into the canal, weights were wired to her ankles and wrists which could have caused her extremities to become severed in the months her corpse spent in the water.

Tsokos realized that the optimum way to confirm or deny the identity of the body as that of Luxemburg's was to use DNA testing. His team had initially hoped to find traces of DNA on old postage stamps that Luxemburg had licked, but it transpired that Luxemburg had never done this, preferring to moisten stamps with a damp cloth instead. They therefore opted to find a surviving blood relative and in July 2009 the German Sunday newspaper Bild am Sonntag reported that a great - niece of Rosa Luxemburg's had been located, 79 year old Irene Borde, who donated some strands of her hair for purposes of DNA comparison testing.

In December 2009 it was reported that Berlin authorities had seized the corpse to perform an autopsy before burying it in Luxemburg's grave.

The Berlin Public Prosecutor's office announced in late December 2009 that while there were indications that the corpse was that of Rosa Luxemburg, they had not been enough to provide conclusive proof. In addition, DNA extracted from the hair of Luxemburg's niece did not match that belonging to the cadaver; Tsokos had earlier said that the chances of a match were only 40%. The remains were to be buried at an undisclosed location, while testing was to continue on tissue samples.

The Dialectic of Spontaneity and Organization was the central feature of Luxemburg's political philosophy, wherein "spontaneity" is a grass roots approach to organizing a party - oriented class struggle. Spontaneity and organization, she argued, are not separable or separate activities, but different moments of one political process; one does not exist without the other. These beliefs arose from her view that class struggle evolves from an elementary, spontaneous state to a higher level:

"The working classes in every country only learn to fight in the course of their struggles.... Social democracy... is only the advance guard of the proletariat, a small piece of the total working masses; blood from their blood, and flesh from their flesh. Social democracy seeks and finds the ways, and particular slogans, of the workers' struggle only in the course of the development of this struggle, and gains directions for the way forward through this struggle alone."

Luxemburg did not hold "spontaneism" as an abstraction, but developed the Dialectic of Spontaneity and Organization under the influence of mass strikes in Europe, especially the Russian Revolution of 1905. Unlike the social democratic orthodoxy of the Second International, she did not regard organization as a product of scientific - theoretic insight to historical imperatives, but as product of the working classes' struggles:

"Social democracy is simply the embodiment of the modern proletariat's class struggle, a struggle which is driven by a consciousness of its own historic consequences. The masses are in reality their own leaders, dialectically creating their own development process. The more that social democracy develops, grows and becomes stronger, the more the enlightened masses of workers will take their own destinies, the leadership of their movement, and the determination of its direction into their own hands. And as the entire social democracy movement is only the conscious advance guard of the proletarian class movement, which in the words of the Communist Manifesto represent in every single moment of the struggle the permanent interests of liberation and the partial group interests of the workforce vis à vis the interests of the movement as whole, so within the social democracy its leaders are the more powerful, the more influential, the more clearly and consciously they make themselves merely the mouthpiece of the will and striving of the enlightened masses, merely the agents of the objective laws of the class movement."

and

"The modern proletarian class does not carry out its struggle according to a plan set out in some book or theory; the modern workers' struggle is a part of history, a part of social progress, and in the middle of history, in the middle of progress, in the middle of the fight, we learn how we must fight... That's exactly what is laudable about it, that's exactly why this colossal piece of culture, within the modern workers' movement, is epoch defining: that the great masses of the working people first forge from their own consciousness, from their own belief, and even from their own understanding the weapons of their own liberation."

In an article published just before the October Revolution, Luxemburg characterized the Russian February Revolution of 1917 as a "revolution of the proletariat", and said that the "liberal bourgeoisie" were pushed to movement by the display of "proletarian power." The task of the Russian proletariat, she said, was now to end the "imperialist" world war, in addition to struggling against the "imperialist bourgeoisie." The world war made Russia ripe for a socialist revolution. Therefore "the German proletariat are also ... posed a question of honor, and a very fateful question."

In several works, including an essay written from jail and published posthumously by her last companion, Paul Levi (publication of which precipitated his expulsion from the Third International) entitled "The Russian Revolution", Luxemburg sharply criticized some Bolshevik policies, such as their suppression of the Constituent Assembly in January 1918, their support for the partition of the old feudal estates to the peasant communes, and their policy of supporting the purported right of all national peoples to "self - determination." According to Luxemburg, the Bolsheviks' strategic mistakes created tremendous dangers for the Revolution, such as its bureaucratization.

Her sharp criticism of the October Revolution and the Bolsheviks was lessened insofar as she compared the errors of the revolution and of the Bolsheviks with the "complete failure of the international proletariat."

Bolshevik theorists such as Lenin and Trotsky responded to this criticism by arguing that Luxemburg's notions were classical Marxist ones, but did not fit Russia in 1917. They stated that the lessons of actual experience, such as the confrontation with the bourgeois parties, had forced them to revise the Marxian strategy. As part of this argument, it was pointed out that after Luxemburg herself got out of jail, she was also forced to confront the National Assembly in Germany – a step which they compared with their own conflict with the Constituent Assembly.

"In this erupting of the social divide in the very lap of bourgeois society, in this international deepening and heightening of class antagonism lies the historical merit of Bolshevism, and with this feat – as always in large historic connections – the particular mistakes and errors of the Bolsheviks disappear without trace.

After the October Revolution, it becomes the "historic responsibility" of the German workers to carry out a revolution for themselves, and thereby end the war. When a revolution also broke out in Germany in November 1918, Luxemburg immediately began agitating for a social revolution:

"The abolition of the rule of capital, the realization of a socialist social order – this, and nothing less, is the historical theme of the present revolution. It is a formidable undertaking, and one that will not be accomplished in the blink of an eye just by the issuing of a few decrees from above. Only through the conscious action of the working masses in city and country can it be brought to life, only through the people's highest intellectual maturity and inexhaustible idealism can it be brought safely through all storms and find its way to port."

The social revolution demands that power is in the hands of the masses, in the hands of the workers' and soldiers' councils. This is the program of the revolution. It is, however, a long way from soldier – from the "Guards of the Reaction" (Gendarmen der Reaktion) – to revolutionary proletarian.

• Luxemburg's best known quotation is: Freedom is always the freedom of the one who thinks differently (Freiheit ist immer Freiheit der Andersdenkenden), this is from a fuller quotation:

Freedom only for the supporters of the government, only for the members of a party – however numerous they may be – is no freedom at all. Freedom is always the freedom of the dissenter. Not because of the fanaticism of "justice", but rather because all that is instructive, wholesome, and purifying in political freedom depends on this essential characteristic, and its effects cease to work when "freedom" becomes a privilege.

• "Without general elections, without unrestricted freedom of press and assembly, without a free struggle of opinion, life dies out in every public institution, becomes a mere semblance of life, in which only the bureaucracy remains as the active element".

• "For us there is no minimal and no maximal program; socialism is one and the same thing: this is the minimum we have to realize today".

• "We stand today... before the awful proposition: either the triumph of imperialism and the destruction of all culture, and, as in ancient Rome, depopulation, desolation, degeneration, a vast cemetery; or, the victory of socialism."

Luxemburg's last known words, written on the evening of her murder, were about her belief in the masses, and in what she saw as the inevitability of revolution:

"The leadership has failed. Even so, the leadership can and must be recreated from the masses and out of the masses. The masses are the decisive element, they are the rock on which the final victory of the revolution will be built. The masses were on the heights; they have developed this 'defeat' into one of the historical defeats which are the pride and strength of international socialism. And that is why the future victory will bloom from this 'defeat'.

'Order reigns in Berlin!' You stupid henchmen! Your 'order' is built on sand. Tomorrow the revolution will already 'raise itself with a rattle' and announce with fanfare, to your terror:
I was, I am, I shall be!"

In Berlin Mitte, the Rosa - Luxemburg - Platz and a U-Bahn station were named in her honor by the East German government. The Volksbühne (People's Theater) is in Rosa - Luxemburg - Platz. The names remain unchanged since reunification in 1989.

During the People's Republic of Poland, in Warsaw's Wola district, a manufacturing facility of electric lamps, was established and named "Imienia Róży Luksemburg" after Polish spelling of her name (Róża Luksemburg).

In 1919, Bertolt Brecht wrote the poetic memorial Epitaph honoring Rosa Luxemburg, and, in 1928, Kurt Weill set it to music as The Berlin Requiem:

Red Rosa now has vanished too. (...)

She told the poor what life is about,

And so the rich have rubbed her out.

May she rest in peace.

The British New Left historian Isaac Deutscher wrote of Rosa: "In her assassination Hohenzollern Germany celebrated its last triumph and Nazi Germany its first".

Reactionaries had a much different understanding of Luxemburg's murder, particularly common among the Russian White emigres who settled in Weimar Berlin. According to one,

"Infamous, that fifteen thousand Russian officers should have let themselves be slaughtered by the Revolution without raising a hand in self - defense! Why didn't they act like the Germans, who killed Rosa Luxemburg in such a way that not even a smell of her has remained?"

In Barcelona there are terraced gardens named in her honor.

At the edge of the Tiergarten, on the Katharina - Heinroth - Ufer, which runs between the southern bank of the Landwehr Canal and the bordering Zoologischer Garten (Zoological Garden) a memorial has been installed on which the name of Rosa Luxemburg appears in raised capital letters, marking the spot where her body was thrown into the canal by Freikorps troops.

After their deaths, Karl Liebknecht and Rosa Luxemburg became martyrs for Marxists. According to the Federal Office for the Protection of the Constitution, commemoration of Liebknecht and Luxemburg continues to play an important role among the German far left.

Liebknecht was born in Leipzig, the son of Wilhelm Martin Philipp Christian Ludwig Liebknecht and his second wife Natalie (née Reh), who also came from a family with a strong political background; her father, Karl, was a member of the Frankfurt Parliament of 1848. Liebknecht's parents were second cousins; his maternal great - grandmother was the sister of one of his paternal great - grandfathers.

His father, Wilhelm Liebknecht, was one of the founders of the Social Democratic Party of Germany. However, Karl Liebknecht was more radical than his father; he became an exponent of Marxist ideas during his study of law and political economy in Leipzig and Humboldt University of Berlin. After serving with the Imperial Pioneer Guards in Potsdam from 1893 to 1894 and internships in Arnsberg and Paderborn from 1894 to 1898, he earned his doctorate at Würzburg in 1897 and moved to Berlin in 1899, where he opened a lawyer's office with his brother, Theodor. Liebknecht married Julia Paradies on 8 May 1900; the couple had two sons and a daughter before Liebknecht's wife died in 1911.

As a lawyer, Liebknecht often defended other left wing socialists who were tried for offenses such as smuggling socialist propaganda into Russia, a task in which he was also involved. He became a member of the SPD in 1900 and was president of the Socialist Youth International from 1907 to 1910. Liebknecht also wrote extensively against militarism, and one of his papers, Militarismus und Antimilitarismus ("militarism and antimilitarism") led to his being arrested in 1907 and imprisoned for 18 months in Glatz, Prussian Silesia. In the next year he was elected to the Prussian parliament, despite still being in prison.

Liebknecht was an active member of the Second International and a founder of the Socialist Youth International. In 1912 Liebknecht was elected to the Reichstag as a Social Democrat, a member of the SPD's left wing. He opposed Germany's participation in World War I, but in order not to infringe the party's unity he abstained from the vote on war loans on 4 August 1914. On 2 December 1914 he was the only member of the Reichstag to vote against further loans, the supporters of which included 110 of his own Party members. He continued to be a major critic of the Social Democratic leadership under Karl Kautsky and its decision to acquiesce in going to war. In October that year, he also married his second wife, art historian Sophie Ryss.

At the end of 1914, Liebknecht, together with Rosa Luxemburg, Leo Jogiches, Paul Levi, Ernest Meyer, Franz Mehring and Clara Zetkin formed the so-called Spartacus League (Spartakusbund); the league publicized its views in a newspaper titled Spartakusbriefe ("Spartacus Letters") which was soon declared illegal. Liebknecht was arrested and sent to the eastern front during World War I despite his immunity as a member of parliament; refusing to fight, he served burying the dead, and due to his rapidly deteriorating health was allowed to return to Germany in October 1915.

Liebknecht was arrested again following a demonstration against the war in Berlin on 1 May 1916 that was organized by the Spartacus League, and sentenced to two and a half years in jail for high treason, which was later increased to four years and one month.

Liebknecht was released again in October 1918, when Max von Baden granted an amnesty to all political prisoners, on his return to Berlin on 23 October he was escorted to the Soviet embassy by a crowd of workers. Following the outbreak of the German Revolution, Liebknecht carried on his activities in the Spartacist League; he resumed leadership of the group together with Luxemburg and published its party organ, Die Rote Fahne (The Red Flag).

On 9 November, Liebknecht declared the formation of a Freie Sozialistische Republik (Free Socialist Republic) from a balcony of the Berliner Stadtschloss, two hours after Philipp Scheidemann's declaration of a German Republic from a balcony of the Reichstag.

On 31 December 1918/1 January 1919, Liebknecht was involved in the founding of the KPD. Together with Luxemburg, Leo Jogiches and Clara Zetkin, Liebknecht was also instrumental in the January 1919 Spartacist uprising in Berlin. Initially he and Luxemburg opposed the revolt, but participated after it had begun. The uprising was brutally opposed by the new German government under Friedrich Ebert with the help of the remnants of the Imperial German Army and militias called the Freikorps; by 13 January, the uprising had been extinguished. Liebknecht and Luxemburg were captured by Freikorps gangs, on 15 January 1919, with considerable support from Minister of MSPD Defense Gustav Noske, and brought to the Eden Hotel in Berlin, where they were tortured and interrogated for several hours. Following this, Luxemburg was beaten with rifle butts and afterwards shot, her corpse thrown into a nearby river while Liebknecht was forced to step out of the car where he was being transported and then shot in his back. Official declarations later claimed he had been shot in an attempt to escape. Although the circumstances were disputed by the perpetrators at the time the Freikorps commander Captain Waldemar Pabst would later claim "I had them executed".

In 1930 the Soviet government renamed a village near Kursk after him in central Russia - Imeni Karla Libknekhta.