In 1960, 70 black protesters were killed during a peaceful demonstration in Sharpesville. The African National Congress (ANC), the principal antiapartheid organization, was banned that year, and in 1964 its leader, Nelson Mandela, was sentenced to life imprisonment. Black protests against apartheid grew stronger and more violent. In 1976, an uprising in the black township of Soweto spread to other black townships and left 600 dead. Beginning in the 1960s, international opposition to apartheid intensified. The UN imposed sanctions, and many countries divested their South African holdings.