Complex sentence: In 1983, he became the Vice President of the United Democratic Front coalition and in 1985, chairman of the Release Mandela campaign which advocated for ANC leader Nelson Mandela's release from prison.
Split into simpler sentences: In 1983, he became the Vice President of the United Democratic Front coalition. In 1985, he served as the chairman of the Release Mandela campaign which advocated for ANC leader Nelson Mandela's release from prison.