Complex sentence: Under the apartheid government, only whites were held in the Old Fort itself, except for Nelson Mandela, who was given a bed in the hospital section when he was as an awaiting-trial prisoner in 1962 prior to the Rivonia Trial.
Split into simpler sentences: Under the apartheid government, only whites were held in the Old Fort itself. But blacks where held as awaiting-trial prisoners, such as Nelson Mandela, who was given a bed in the hospital section when he was as an awaiting-trial prisoner in 1962 prior to the Rivonia Trial.