22 April 1960
On 22 April 1960, about 1,575 people were detained under South Africa's state of emergency that was declared by the South African government on 30 March 1960. The move by the government to declare the state of emergency came nine days after the Sharpeville massacre where nearly 70 people were killed by security police and scores left injured. During the same month the African National Congress (ANC), Pan Africanist Congress (PAC), and other liberation movements were banned by government under the Unlawful Organisations Act.
References

Boddy-Evans A. ‘This Day in Africa History: 22 April’, in African History, 22 April. South African History Online, ‘State of Emergency follows Sharpeville massacre’, [online], Available at www.sahistory.org.za [Accessed: 16 March 2012]|Katriena K. ‘Today’s History’, in the Perswildebeest.proboards, 15 April 2008