Armageddon vs theater of operations

Armageddon

name
  • Mount Megiddo, the site of a prophesied final battle between the forces of good and evil. 

  • Any end of the world, especially by way of a cataclysmic battle or something analogous to one. 

  • The battle itself. 

theater of operations

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