gunship vs infantryman

gunship

noun
  • A ship equipped with heavy artillery. 

  • An armed helicopter tasked to attack the enemy. 

  • A transport airplane equipped with large calibre guns typical of armoured fighting vehicles 

infantryman

noun
  • a male soldier of the infantry 

  • a soldier employed in an infantry role 

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