belligerence vs mettle

belligerence

noun
  • The state of being belligerent; aggressive inclination to war. 

mettle

noun
  • Good temperament and character. 

  • A quality of endurance and courage. 

adj
  • Spirited, vigorous, stout-hearted. 

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