“a civil war that they started.
(do I have my history correct here?)”
Only partly. The ANC attempted for years to change the Apartheid system through peaceful democratic means. But the response from the Apartheid leaders was to deny them the right to vote, with eventual plans to strip them of their citizenship! They probably learned this from the Nazis whom so many had supported during WW2. So the ANC did start an “armed struggle” and Mandela was indeed guilty of being part of that (hence his 27 years in prison, originally a death sentence). But the ANC never put a lot of effort into its “armed struggle”, preferring to arrange for a worldwide sanctions and divestment effort. Which worked.