befall vs occur

befall

verb
  • To happen. 

  • To fall upon; fall all over; overtake 

  • To happen to. 

noun
  • Case; instance; circumstance; event; incident; accident. 

occur

verb
  • To happen or take place. 

  • To present or offer itself. 

  • To be present or found. 

  • To come or be presented to the mind; to suggest itself. 

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