fall upon vs rough up

fall upon

verb
  • to set upon; to attack suddenly 

  • to occur at some particular point in time. 

  • to experience; to suffer. 

rough up

verb
  • to manhandle or beat up 

  • To make rough, to roughen (especially doing so to wood while raising the grain) 

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