Conversation so far:
What happened during Apartheid?
Winnie was regularly detained by the National Party government.
She was tortured, subjected to house arrest, kept under surveillance, held in solitary confinement for over a year and.
And what else?
and even banished to a remote town.
She emerged as a leading opponent of apartheid during the later years of her husband's imprisonment.
What did she do to fight Apartheid?
).
For many of those years, she was banished to the town of Brandfort in the Orange Free State and confined to the area, except.
Except what happened?
except for when she was allowed to visit her husband at Robben Island.
Beginning in 1969, she spent eighteen months in solitary confinement at Pretoria Central Prison.

Question: Why did she go to prison?
Self-contained rewrite: Why did Winnie go to prison?