Conversation so far:
When did Winnie Madikizela-Mandela die?
Winnie Madikizela-Mandela died on 2 April 2018 at the age of 81.
How did Winnie Madikizela-Mandela die?
Winnie Madikizela-Mandela suffered from diabetes and had recently undergone several major surgeries. She had been in and out of hospital since the start of the year.

Question: When was her funeral?
Self-contained rewrite: When was Winnie Madikizela-Mandela's funeral?