fall upon vs invade

fall upon

verb
  • to set upon; to attack suddenly 

  • to occur at some particular point in time. 

  • to experience; to suffer. 

invade

verb
  • To attack; to infringe; to encroach on; to violate. 

  • To move into. 

  • To enter by force in order to conquer. 

  • To infest or overrun. 

  • To make an unwelcome or uninvited visit or appearance, usually with an intent to cause trouble or some other unpleasant situation. 

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