Conversation so far:
Does Voldemort appear in Harry Potter and the Half-Blood Prince?
Voldemort does not appear in Harry Potter and the Half-Blood Prince.
Was there any flashbacks?
In a series of flashbacks, using the pensieve as a plot device.
Who was the author of Harry Potter and the Half-Blood Prince?
Rowling.
Did Voldemort have to assault anyone?
He murders Amelia Bones of the Department of Magical Law Enforcement.

Question: Did he have to fight any hogwarts?
Self-contained rewrite: Did Lord Voldemort have to fight any hogwarts in Harry Potter and the Half-Blood Prince?