blitzkrieg vs onslaught

blitzkrieg

noun
  • A fast military offensive, typically involving a large and highly mobile tank force with air support. 

onslaught

noun
  • A fierce attack. 

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

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