Conversation so far:
When did P.
W.
Botha enter Parliament?
At age 30, Botha was elected head of the National Party Youth in 1946.
What happened to him after that?
and two years later won a race for the House of Assembly.

Question: When did he win that election?
Self-contained rewrite: When did P. W. Botha win the race for the House of Assembly election?