RADEK (Sobelsohn), KARL (1885–1939?), Russian revolutionary and publicist. Born in Lemberg, Radek was a member of the Polish Social Democratic Party, for which he wrote many articles. Before World War I he was also active as a publicist for the left wing of the German Social Democratic Party. During the war he played a prominent part in the Zimmerwald and Kintal pacifist conferences. After the Russian Revolution broke out in February 1917, Radek was one of those who accompanied Lenin on his famous journey from Switzerland through Germany to Sweden in a sealed railroad car. He remained in Sweden as a representative of the Bolshevik Party, but after the October Revolution he returned to Russia and became head of the Central European section of the Foreign Affairs Commissariat. In 1918, when revolution broke out in Germany, Radek entered the country secretly and helped to organize the first congress of the German Communist Party. In 1920 he proposed and supported the idea of a "united front" of the German Communists and Social Democrats. He was arrested in February 1919 but was released at the end of the year. He was one of the leaders of the group which opposed the Brest-Litovsk agreement with Germany. He returned to the U.S.S.R. and in 1922 became a leading official of the Communist International. In this capacity he maintained contact with communist-oriented Zionists of the "left *Po'alei Zion faction" who applied for admission into and recognition by the Communist International. In 1924, however, he joined the Trotskyite opposition and in 1927 was expelled from the party and banished to the Ural mountains. He was readmitted in 1930 on renouncing his adherence to the Trotskyists. Just before his banishment he had served for a year as rector of the Sun Yat-Sen University for Chinese students in Moscow.
In the 1930s Radek was an influential writer and speaker on international affairs and was a regular contributor to Pravda and Izvestia. He was the coauthor of the draft of the so-called "Stalin constitution" of the U.S.S.R. (1936). Radek's writings include In den Reihen der deutschen Revolution 1909–1919 (1921) and many articles on literature and the theater. In 1937 Radek was arrested and charged with complicity in plots against the Soviet government. At a show trial which received worldwide publicity, with the prisoners compelled to make dramatic and abject confessions, he was convicted of being "an enemy of the people" and was sentenced to ten years' imprisonment. On May 19, 1939, he was killed by criminal prisoners in the prison, probably by the order of the leadership. In 1988 he was rehabilitated by the Supreme Court of the U.S.S.R. A selection of his works, Portraits and Pamphlets, appeared in 1935.
L. Schapiro, The Communist Party of the Soviet Union (1960), index; E.H. Carr, The Bolshevik Revolution 1917–1923, 3 (1966), index; idem, Socialism in One Country, 3, Pt. 2 (1964), index; D. Collard, Soviet Justice and the Trial of Radek and Others (1937); R. Conquest, Great Terror (1968), index.