man-of-war vs warfighter

man-of-war

noun
  • A man whose occupation is fighting in wars; a soldier, a warrior. 

  • A powerful armed naval vessel, primarily one armed with cannon and propelled by sails; a warship. 

  • The Arctic skua (Stercorarius parasiticus). 

warfighter

noun
  • A soldier (especially of the United States military). 

How often have the words man-of-war and warfighter occurred in a corpus of books? (source: Google Ngram Viewer )