intrepidity vs mettle

intrepidity

noun
  • The quality of being intrepid; bravery. 

mettle

noun
  • A quality of endurance and courage. 

  • Good temperament and character. 

adj
  • Spirited, vigorous, stout-hearted. 

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