Leon "Leo" Jogiches[1] (Russian: Лев "Лео" Йогихес; 17 July 1867 – 10 March 1919), also commonly known by the party name Jan Tyszka, was a Polish Marxist revolutionary and politician, active in Poland, Lithuania, and Germany.

[4][5] Little is known of his childhood years, although it is perhaps instructive that Jogiches spoke no Hebrew and had no more than a rudimentary grasp of Yiddish, indicating a closer familiarity with other regional languages and cultures than those of his Jewish heritage.

[7] Not to be deterred by the clash of egos and the dispute over money, Jogiches would nevertheless proceed to establish his publishing house, The Social-Democratic Library (Sotsialdemokraticheskaya Biblioteka) in 1892, issuing pirated editions of works by Marx, Karl Kautsky, and others — further poisoning relations with Plekhanov.

[10] The Russian Revolution of 1905 erupted abruptly on "Bloody Sunday," 22 January with the shooting deaths of hundreds of peaceful protesters who were attempting to present a petition to Tsar Nicholas II.

Within days, protests and strikes calling for establishment of a constitutional order swept the empire, which rocked the state censorship and threatened the stability of the government for months.

[16] Within the SPD Luxemburg, drawing upon the ongoing Russian experience, pushed the idea of the "mass strike" as a strategic tool for the achievement of power, over the objections of trade unionists and more conservative and electorally-driven party leaders.

[18] As part of an ongoing battle to radicalize the party's daily newspaper, Vorwärts (Forward), Luxemburg was named to the paper's editorial board in the fall of 1905.

[22] Consequently, the chief contribution of Jogiches was that of literary stimulant to the skilled publicist Luxemburg as well as behind-the-scenes organizer of the fledgling underground political party that he had helped to establish.

During 1909, Jogiches formed a tactical alliance with the Bolshevik leader, Vladimir Lenin, and backing him as he tried to gain control of the Russian Social Democratic Labour Party, by excluding the Mensheviks.

[27] Rosa Luxemburg's immediate inclination was to publish and clandestinely circulate a manifesto signed by anti-war leaders of the SPD calling for spontaneous resistance — an effort which Jogiches criticized as no substitute for actual political organization.

[29] These included Leo Jogiches, Julian Marchlewski, Franz Mehring, and Klara Zetkin, her lawyer Paul Levi, and second secretary of the SPD in Berlin Wilhelm Pieck, among others.

[30] Imperial authorities were not deaf to the threat of anti-war radicalism gaining a foothold and conscripted left wing parliamentary official Karl Liebknecht on 7 February 1915, only to begin transferring him from one military unit to another in an effort to isolate him and neutralize his influence.

[32] A formal conference was held on 5 May 1915, in the apartment of Wilhelm Pieck to discuss a regional system of organization, which was conceived as a secret network of anti-war militants operating within the SPD.

[38] As leader of the underground organization it was Jogiches that oversaw the publication of the official newsletter Spartacus, launched in September 1916, which gave a new name to the faction — the Spartakusbund, rendered into English as the Spartacist League.

A Congress was held at Gotha during Easter 1917 by the pacifist center and revolutionary left socialists, with the gathering launching a new organization, the Independent Social Democratic Party of Germany (USPD).

[41] Jogiches would remain in the role of the underground Spartacist group until his own arrest in Berlin on 24 March 1918, at which time the leadership of the Spartacus League passed into the hands of Paul Levi.