1948: Afrikaner National Party wins general election on apartheid platform and begins implementing discriminatory policies.
1951: Nelson Mandela becomes ANC Youth League President.
1952: Start of the “Defiance Campaign.” Blacks, coloreds and Indians use "white-only" facilities and break nighttime curfews. Also that year, Mandela and Mr. Tambo found South Africa’s first black law firm; they focus on apartheid cases related to persecution of black Africans.
1955: Mandela helps develop the Freedom Charter, the precursor to South Africa's democratic constitution; it is launched in Kliptown, Soweto.
1956: Mandela and 155 others are arrested and tried for treason. After a four-year trial, they are acquitted.