duel vs gunfight

duel

verb
  • To engage in a battle. 

noun
  • Arranged, regular combat between two private persons, often over a matter of honor. 

  • Historically, the wager of battle (judicial combat). 

  • Any battle or struggle between two contending persons, forces, groups, or ideas. 

gunfight

verb
  • To engage in battle using small arms. 

noun
  • A battle (or a duel) using small arms. 

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