beleaguer vs oppress

beleaguer

verb
  • To besiege; to surround with troops. 

  • To exhaust. 

  • To vex, harass, or beset. 

oppress

verb
  • To keep down by unjust force. 

  • To make sad or gloomy. 

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