Baruch Hirson, named after his late grandfather, was born on 10 December 1921 at Doomfontein near Johannesburg in the Transvaal. His father was an electrician. His parents, Joseph and Lily Hirson, were Jews who had immigrated to South Africa to evade the pogroms, persecution and discrimination Jews were subjected to in the old Romanov empire.

At the age of four, Hirson was enrolled at the Talmud Torah, a Hebrew school in Johannesburg. Baruch had a great mathematical ability and insight and studied as a part-time student at the University of Witwatersrand. This allowed him to move up the educational hierarchy of the university, later working as a teacher and lecturer at Witwatersrand University.

After matriculating in 1939, he joined Zionist Youth Clubs and groups. In 1940 he became a member of the left-wing Hashomer Hatzairgroup. A few years later Hirson became a member of Fourth International Organisation of South Africa (FIOSA), started studying Marxist literature and advocated anti-Zionist positions. Between 1944 and 1946 he worked for the Workers International League, a South African Trotskyist group, as a full-time political organiser and became a key figure in the organisation. However, similar to other Trotskyist groups at the time, the League was in the doldrums and politically quite isolated. As a result, it could not develop into a real political party.

Nevertheless, this situation never despaired Hirson and his colleagues. They strove to set up black trade unions, undertaking this cause under extremely difficult conditions created by the oppressive Suppression of Communism Act. Hirson's participation in politics grew. With other South African Trotskyists, he became involved in the Non-European Unity Movement (NEUM) and in 1950 joined the Congress of Democrats (COD), the white arm of the Congress Alliance, which was led by the ANC.

After Sharpeville massacre in 1960, Trotskyists around Hirson, organised in a National Committee for Liberation (later called African Resistance Movement, ARM) and other faction in the ANC adopted radical method in dealing with the government, for example sabotage as a substitute for peaceful action. In 1964 he was arrested and convicted of sabotage. He was sentenced to 9 years imprisonment and served the time in the Johannesburg Fort, Pretoria Local and Pretoria Central jails. When was released in 1973, Hirson was confronted with a banning order and house arrest and immediately decided to go into exile with his wife and three children. They arrived in England in1973 and Hirson managed to find himself a job at Bradford University and later at Middlesex University. He lectured in physics for several years and in 1986 he enrolled for a doctorate in history. His wife was working as pediatrician.

Hirson never made it back to South Africa since the fall of apartheid, except in 1991 when he came for a short visit to participate in a conference on Marxism. However, Hirson managed to author excellent and meticulously researched history documents and biographies. The documents and books he published includes a chronology of the famous Soweto Uprising (Year of fire, year of ash, 1979), an account of working-class rebellion in South Africa (Yours for the union, 1989) to mention just a few. During the last years of his life, he maintained correspondence with the Chinese veteran Trotskyist, Wang Fanxi, and American photographer and ex-guard of Leon Trotsky, Alex Buchman.

In the1990s his health gradually deteriorated and he was housebound until his death in London Hospital on 3 October 1999 at the age of 77. He is survived by his wife Yael and their three children.

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