blitzkrieg vs bombardment

blitzkrieg

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

bombardment

noun
  • heavy artillery fire 

  • the act of bombing, especially towns or cities 

  • the incidence of an intense stream of high-energy particles directed at a substance 

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