The banning of the South African black opposition - the African National Congress (ANC) and the Pan Africanist Congress (PAC) - in 1960 and the repression of African trade unions thereafter discouraged most forms of African organisation during the 1960s. After they were banned, the ANC and the PAC adopted revolutionary strategies aiming at the radical transformation of South African society through, among other things, armed struggle. The subsequent clampdown on political organisations led to the arrest and imprisonment of some of their leaders, such as Nelson Mandela and Robert Sobukwe. The ANC and the PAC then established missions-in-exile, leaving an organisational vacuum in the country which was partly filled by the Black Consciousness Movement (BCM) during the 1970s.