(party pseudonyms, Mechanik; Marcin Grzegorzewski). Born Jan. 1, 1881; died Dec. 25, 1937. Figure in Polish and Russian revolutionary movements.
Grzelszczak was born in Warsaw. In 1904 he became a member of the Social Democratic Party of the Kingdom of Poland and Lithuania (SDKPiL). He took part in the Revolution of 1905-07 (in Warsaw). He was a delegate to the Fifth (London) Congress of the RSDLP. In 1914 he was called up for military service. He took part in the revolutionary movement in the army. At the All-Russian Democratic Conference in Petrograd in September 1917, he was elected to the pre-Parliament, which he then left together with the Bolshevik faction. At the Second Congress of Soviets on Oct. 26 (Nov. 8), 1917, he was elected a member of the All-Russian Central Executive Committee. In the beginning of 1918 he left for Poland. In December 1918 he became a member of the Central Committee of the Communist Party of Poland and took part in all its congresses and conferences. He was arrested in May 1925, and in 1928 he returned to the USSR with other political prisoners as part of a trade with the Soviet government. He took part in the Fourth, Fifth, Sixth, and Seventh Congresses of the Comintern. At the Fifth Congress of the Comintern in 1924, he was elected to the Executive Committee of the Communist International. From 1924 to 1928 he was a member of the International Control Commission of the Executive Committee of the Communist International. Grzelszczak also took part in the work of the Profintern (Red International of Trade Unions) and of the MOPR (International Organization for Aid to the Fighters for the Revolution).