The Social Democracy of the Kingdom of Poland and Lithuania (, SDKPiL), , LKLSD), originally the Social Democracy of the Kingdom of Poland (SDKP), was a Marxist political party founded in 1893 and later served as an autonomous section of the Russian Social Democratic Labour Party. It later merged into the Communist Workers Party of Poland. Its most famous member was Rosa Luxemburg. Leading members The leading cadre of the SDKPiL were a famous group, many of whom would play a role in the Russian Revolution of October 1917. Chief among them was Rosa Luxemburg, the leading theoretician of the movement. Other notable figures included Leo Jogiches, Julian Marchlewski, Adolf Warski, Felix Dzerzhinsky, Stanisław Pestkowski, Karl Sobelson, Józef Unszlicht, Kazimierz Cichowski and Jakob Fürstenberg. Internationalists, many of them would play leading roles in Germany as well as in Russia. History 1893: Formation The party was founded in 1893 based on an internationalist Marxist program. At its core was the which refused to back the national demands contained within the program of the Polish Socialist Party (PPS). As a result of the differing positions on the question of Polish national independence the former Union of Polish Workers and the Second Proletariat left the PPS in 1893 establishing the SDKP, differences between the two parties deepening at the International Socialist Congress of August 1893 when the All-Polish delegation, led by Ignacy Daszyński of Galicia opposed seating Karski and Rosa Luxemburg now making her first appearance at an international gathering. Differences were to deepen at the next International Socialist Congress in 1896 where Luxemburg was opposed by the future dictator of Poland, Józef Piłsudski, representing the PPS. 1899: Merger with the Union of Workers in Lithuania Conceived as the geographical representative party of the workers, rather than national, the SDKP was to fuse with the Union of Workers in Lithuania in 1899 as a result of the work carried out by Feliks Dzierżyński, future Bolshevik head of the Cheka. The SDKP becoming the Social Democracy of the Kingdom of Poland and Lithuania. The young party enjoyed a period of growth impelled by the organisational efforts of Dzierżyński in Warsaw before he was arrested again. 1903:The split between Bolsheviks and Mensheviks Consistent with its self-conception as a geographic unit of an All-Russian Social Democratic party, the SDKPiL attended the 1903 Congress of the Russian Social Democratic Labour Party (RSDLP) held in London at which