conventional warfare vs guerrilla warfare

conventional warfare

noun
  • The waging of war in a manner which does not use nuclear, biological, or chemical weapons. 

  • The waging of war in set military battles, as opposed to waging guerrilla warfare or fighting insurgencies. 

guerrilla warfare

noun
  • Combat using groups of irregular, light, mobile troops within areas occupied by an enemy force, usually through hit-and-run tactics. 

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