night of the long knives vs witch-hunt

night of the long knives

noun
  • A purge, in which opponents of a regime or political party are killed or removed. 

witch-hunt

noun
  • A public or political campaign or investigation which smears a person or group. 

  • An attempt to find and punish or harass a group of people perceived as a threat, usually on ideological or political grounds. 

  • A search for people believed to be using sorcery or harmful magic, typically in order to persecute or punish them. 

verb
  • To perform a witch-hunt. 

How often have the words night of the long knives and witch-hunt occurred in a corpus of books? (source: Google Ngram Viewer )