courage vs fortitude

courage

noun
  • The ability to maintain one's will or intent despite either the experience of fear, frailty, or frustration; or the occurrence of adversity, difficulty, defeat or reversal. Moral fortitude. 

  • The ability to overcome one's fear, do or live things which one finds frightening. 

  • The quality of being confident, not afraid or easily intimidated, but without being incautious or inconsiderate. 

fortitude

noun
  • Mental or emotional strength that enables courage in the face of adversity. 

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