1961, 21 December
Moïse Kapenda Tshombe agrees to a unification of the Congo.
1967, 21 December
Louis Washkansky, the world's first heart transplant patient dies. The heart was obtained from a 24-year-old motor-accident victim, Denise Darvall, and was transplanted by Dr Christiaan Barnard only 18 days before. (Previous -> 3 December 1967: First heart transplant.)