12 May 1968
On 12 May 1968, South African academic, African National Congress (ANC) politician, and Botswana's first ambassador to the USA and envoy to the UN, Zachariah Keodirelang (ZK) Matthews, died in Washington, USA. He was buried in Gaborone, Botswana.  "Bridging the gap between the old guard and the more militant younger members of the African National Congress in the late 1940s and 1950s, Zachariah Keodirelang Matthews exercised a major guiding and moderating influence on African political history in its most crucial period. He was at the same time South Africa's, and perhaps the continent's, most distinguished African intellectual"
References

Matthews, ZK., (2011), 'A biography of ZK Matthews', from South African history online, [online], Available at www.sahistory.org.za/people/bios/matthews,z.htm|Verwey, E.J. (ed)(1995). New Dictionary of South African Biography, v.1 , Pretoria: HSRC, p. 163.|Potgieter, D.J. et al. (eds)(1970). Standard Encyclopaedia of Southern Africa, Cape Town: NASOU, v.7, p. 245).|Maharaj, M., (2001), 'Address by President Thabo Mbeki at the Inaugural ZK Matthews Memorial Lecture. University of Fort Hare', from Nelson Mandela Organisation, 12 October, [online], Available at https://www.nelsonmandela.org/omalley/index.php/site/q/03lv03445/04lv04206/05lv04302/06lv04303/07lv04304.htm [Accessed: 28 May 2014]