irruption vs onslaught

irruption

noun
  • The action of irrupting or breaking into; a violent entry or invasion; an inbreaking; an intrusion. 

  • An abrupt increase in the size of a movement or organization. 

  • An abrupt increase of an animal population. 

onslaught

noun
  • A fierce attack. 

  • A large number of people or things resembling an attack. 

How often have the words irruption and onslaught occurred in a corpus of books? (source: Google Ngram Viewer )