19 January 1989
Chris Heunis, Minister of Constitutional Development and Planning, was appointed Acting State President by President P.W. Botha who was recovering from a mild stroke suffered on 18 January. Botha surprised everyone when he resigned from the National Party (NP) leadership but not as state president, where he continued to make key decisions, although recovering from a stroke.
References
nelsonmandela,'19 January 1989',[Online] Available at: www.nelsonmandela.org, [Accecessed on: 17 December 2013]