Semaun (approx. 1899—1971) was the first chairman of the Communist Party of Indonesia (PKI).
Early life 
Semaun was born in Curahmalang, Jombang, East Java. In 1915 at the age of sixteen, he was elected as one of the first Indonesian members of the Union of Train and Tramway Personnel (VSTP), soon quitting his job as a railway worker to become a trade union activist full-time. Also in 1915 he was elected vice-chairman of the Surabaya office of the Indies Social Democratic Association (ISDV), which was to become the PKI. By 1918 he was a member of the central leadership of Sarekat Islam (SI), then the dominant nationalist political organization in the Dutch East Indies.
Communist activities 
In May 1921, when the Communist Party of Indonesia was founded after the deportation of the Dutch founders of the ISDP, Semaun became its first chairman. The PKI initially was a part of Sarekat Islam, but political differences over the role of class struggle and of Islam in nationalism between Semaun's PKI and the rest of SI led to an organizational split by October. At the end of that year he left Indonesia for Moscow, and Tan Malaka replaced him as chairman. Upon his return in May 1922, he regained the chairmanship and tried, with limited success, to restore PKI influence over the sprawling SI organization.
In 1923 VSTP, the railway union, organized a general strike. It was soon crushed by the Dutch government, and Semaun was exiled from the Indies. He returned to the Soviet Union, where he was to remain for more than thirty years. He remained involved as a nationalist activist on a limited basis, speaking a few times to Perhimpunan Indonesia, a Netherlands-based organization of Indonesian students. He also studied at the Communist University of the Toilers of the East for a time.
Upon his return to Indonesia after its independence, Semaun moved to Jakarta, where from 1959 to 1961 he served as a government administrator. He also taught economics at Universitas Padjadjaran in Bandung.
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