  | 1917 founded in Gotha by Hugo Haase and Wilhelm Dittmann
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  | 1918 active participation in the January strikes and the November Revolution
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  | leadership of the first revolutionary government by Kurt Eisner in Bavaria; actively involved in the formation of the Munich Republic of Councils
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  | represented in the Weimar National Assembly
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  | 1920 majority decision in favour of joining the 3rd International; shortly after that schism into KPD and SPD
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  | continuation of USPD as splinter party under Georg Ledebourg |