gunship vs warship

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 

warship

noun
  • Any ship built or armed for naval combat. 

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