In the ranks of South Africa's antiapartheid struggle, Walter Sisulu is second only to his fellow prisoner and best friend, Nelson Mandela. A quarter- century ago, Sisulu and several other underground leaders of the African National Congress were captured on a farm in the Johannesburg suburb of Rivonia. Along with Mandela, they were sentenced to life imprisonment after being convicted in the Rivonia trial on charges of conspiracy to overthrow the government.
Rumors swirled for years that Pretoria was about to free the Rivonia prisoners, but many seasons of hard labor in the limestone quarries on Robben Island taught Sisulu, now...