26 June 1952
Following the adoption of a Programme of Action in the 1949 annual congress, the ANC began the 1950s with mass action campaigns marked by boycotts, strikes and civil disobedience.  On 26 June 1952 the Defiance Campaign, the most dramatic non-violent act of resistance ever seen in South Africa and the first campaign pursued jointly by all racial groups under the leadership of the African National Congress (ANC), the South African Indian Congress (SAIC) and the Coloured People’s Congress, was launched. It was announced on 6 April 1952 that a campaign to mount a mass action against the passing of six unjust laws was going to be held, with the date set for 26 June 1952. A “Day of the Volunteers” on 22 June preceded the opening of the campaign where volunteers signed the following pledge: “I, the undersigned, Volunteer of the National Volunteer Corps, do hereby solemnly pledge and bind myself to serve my country and my people in accordance with the directives of the National Volunteer Corps and to participate fully and without reservations to the best of my ability in the Campaign for the Defiance of Unjust Laws. I shall obey the orders of my leader under whom I shall be placed and strictly abide by the rules and regulations of the National Volunteer Corps framed from time to time. It shall be my duty to keep myself physically, mentally and morally fit.” The Campaign began when the first volunteers, including Nelson Mandela, Yusuf Dadoo and Walter Sisulu defied apartheid laws in Johannesburg and other major city centres.
References

South Africa, ‘Defiance Campaign’, [online], available at www.overcomingapartheid.msu.edu(Accessed: 23 May 2012)|South African History Online, ‘Defiance Campaign 1952’, [online], available at www.sahistory.org.za(Accessed: 23 May 2012)|Boddy-Evans A, ‘This Day In African History’, from About African History, 26 June, [online], available at www.africanhistory.about.com(Accessed: 26 May 2012)