LONDON — In the welter of passion and memory surrounding the decline of Nelson Mandela, a more modest commemoration slipped by a week ago that said much about the role he played as an inspiration in his long years of imprisonment, when the daily grind of struggle against apartheid fell to others who fought in his name.

It was a reminder, too, that the battle to end white rule was fought on many levels, ranging from the activism of anti-apartheid exiles here in London to a brutal shadow war in South Africa itself that offered no quarter to those seeking a new order.

The events of June 27, 1985, offered a particular insight.

On that date, a hit team of secret police officers — white and black — murdered four anti-apartheid activists from Cradock, a pinprick settlement in the remote hinterland of the Eastern Cape, ambushing their car late at night before bludgeoning, shooting, stabbing and burning them to death.

In the shorthand of martyrdom, they became known as the Cradock Four, emblems of a time when the white authorities sought to dismantle such clusters of resistance through a tactic they euphemistically called “permanent removal” from society....