feud vs oppugn

feud

verb
  • To carry on a feud. 

noun
  • A state of long-standing mutual hostility. 

  • An estate granted to a vassal by a feudal lord in exchange for service. 

  • A staged rivalry between wrestlers. 

oppugn

verb
  • To contradict or controvert; to oppose; to challenge or question the truth or validity of a given statement. 

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