Leo Jogiches, the son of a wealthy merchant, was born in Vilna, Russia. One of his friends, Paul Frölich, has argued: "Little is known about the life of this unusual man... A reserved man, he never spoke of his past."
Jogiches moved to Switzerland in 1890 where he met Rosa Luxemburg, Alexandra Kollontai, George Plekhanov and Karl Kautsky. A fellow revolutionary, Bertram D. Wolfe, has pointed out: "Leo Jogiches, three years older than Rosa Luxemburg, was, when he fled to Zurich in 1890, already a fully formed conspirator and revolutionary. Almost immediately, they became linked by a lifelong personal intimacy (without benefit of religious or civil ceremony) and by a lifelong association in the Polish and Russian, and later in the German, movements. The two were as different as two people engaged in a shared life and common enterprise could be. Jogiches was taciturn, stern, gloomy, secretive about his past and his private life, with none of her eloquence or outgoing capacity for friendship. Moreover, he was, as she was not, a consummate conspirator, an able organizer, a natural born faction fighter. Under the conditions of underground life in Poland and Russia, it is doubtful if she could have built a movement without him. She was the ideologist, he the organizer and conspirator."
In 1893 Jogiches joined with Luxemburg to form the Social Democratic Party of Poland. As it was an illegal organization, the party's newspaper, Sprawa Robotnicza (Workers' Cause) was published in Paris. One of his comrades remarked: "He was a very clever and able debater. In his presence one felt that this was no commonplace man. He devoted his whole existence in his work as a socialist, and his followers idolised him."
After the 1905 Revolution Jogiches and Rosa Luxemburg moved to Warsaw where they were soon arrested. After their release they returned to Germany. Jogiches and Rosa Luxemburg took the side of the Mensheviks in their struggle with the Bolsheviks. As a result Vladimir Lenin favoured the Polish section led by Karl Radek over those of Jogiches and Luxemburg.
On 4th August, 1914, Karl Liebknecht was the only member of the Reichstag who voted against Germany's participation in the First World War. He argued: "This war, which none of the peoples involved desired, was not started for the benefit of the German or of any other people. It is an Imperialist war, a war for capitalist domination of the world markets and for the political domination of the important countries in the interest of industrial and financial capitalism. Arising out of the armament race, it is a preventative war provoked by the German and Austrian war parties in the obscurity of semi-absolutism and of secret diplomacy."
Paul Frölich, a supporter of Liebknecht in the Social Democratic Party (SDP), argued: "On the day of the vote only one man was left: Karl Liebknecht. Perhaps that was a good thing. That only one man, one single person, let it be known on a rostrum being watched by the whole world that he was opposed to the general war madness and the omnipotence of the state - this was a luminous demonstration of what really mattered at the moment: the engagement of one's whole personality in the struggle. Liebknecht's name became a symbol, a battle-cry heard above the trenches, its echoes growing louder and louder above the world-wide clash of arms and arousing many thousands of fighters against the world slaughter."
Clara Zetkin later recalled: "The struggle was supposed to begin with a protest against the voting of war credits by the social-democratic Reichstag deputies, but it had to be conducted in such a way that it would be throttled by the cunning tricks of the military authorities and the censorship. Moreover, and above all, the significance of such a protest would doubtless be enhanced, if it was supported from the outset by a goodly number of well-known social-democratic militants.... Out of all those out-spoken critics of the social-democratic majority, only Karl Liebknecht joined with Rosa Luxemburg, Franz Mehring, and myself in defying the soul-destroying and demoralising idol into which party discipline had developed."
Immediately after the vote on war credits in the Reichstag, a group of SDP anti-militarist activists, including Ernest Meyer, Franz Mehring, Wilhelm Pieck, Julian Marchlewski, Hermann Duncker and Hugo Eberlein met at the home of Rosa Luxemburg to discuss future action. They agreed to campaign against the war but decided against forming a new party and agreed to continue working within the SPD.
In May 1915, Karl Liebknecht published a pamphlet, The Main Enemy Is At Home! He argued: "The main enemy of the German people is in Germany: German imperialism, the German war party, German secret diplomacy. This enemy at home must be fought by the German people in a political struggle, cooperating with the proletariat of other countries whose struggle is against their own imperialists. We think as one with the German people – we have nothing in common with the German Tirpitzes and Falkenhayns, with the German government of political oppression and social enslavement. Nothing for them, everything for the German people. Everything for the international proletariat, for the sake of the German proletariat and downtrodden humanity."
Over the next few months members of this group were arrested and spent several short spells in prison. On the release of Luxemburg in February 1916, it was decided to establish an underground political organization called Spartakusbund (Spartacus League). The Spartacus League publicized its views in its illegal newspaper, Spartacus Letters. Like the Bolsheviks in Russia, they began to argue that socialists should turn this nationalist conflict into a revolutionary war.
Dick Howard has argued: "Agitation continued throughout the war; yet the Spartacus League was never very strong. All agitation had to be carried out in strict secrecy, and the leaders were more often than not in jail." Members included Leo Jogiches, Rosa Luxemburg, Karl Liebknecht, Paul Levi, Ernest Meyer, Franz Mehring, Clara Zetkin, Wilhelm Pieck, Julian Marchlewski, Hermann Duncker and Hugo Eberlein.
On 1st May, 1916, the Spartacus League decided to come out into the open and organized a demonstration against the First World War in Berlin. Several of its leaders, including Karl Liebknecht and Rosa Luxemburg were arrested and imprisoned. They were not released until October, 1918, when Max von Baden granted an amnesty to all political prisoners.
In January, 1919, members of the group organized the Spartakist Rising in Berlin. Friedrich Ebert, the leader of the Social Democrat Party and Germany's new chancellor, called in the German Army and the Freikorps to bring an end to the rebellion. By 13th January the rebellion had been crushed and most of its leaders were arrested. Over the next few weeks Karl Liebknecht, Rosa Luxemburg, and hundreds of other members were executed without trial.
Paul Frölich, the author of Rosa Luxemburg: Her Life and Work (1940) has explained what happened: "A short while after Liebknecht had been taken away, Rosa Luxemburg was led out of the hotel by a First Lieutenant Vogel. Awaiting her before the door was Runge, who had received an order from First Lieutenants Vogel and Pflugk-Hartung to strike her to the ground. With two blows of his rifle-butt he smashed her skull. Her almost lifeless body was flung into a waiting car, and several officers jumped in. One of them struck Rosa on the head with a revolver-butt, and First Lieutenant Vogel finished her off with a shot in the head. The corpse was then driven to the Tiergarten and, on Vogel's orders, thrown from the Liechtenstein Bridge into the Landwehr Canal, where it was not washed up until 31 May 1919."
Leo Jogiches was devastated by the news and spent the next few days trying to expose the murderers. He was eventually arrested and on 10th March, 1919, he was executed.