perfidy vs treason

perfidy

noun
  • A state or act of violating faith or allegiance; violation of a promise or vow, or of trust 

  • Specifically, in warfare, an illegitimate act of deception, such as using symbols like the Red Cross or white flag in a false claim of surrender to gain proximity to an enemy for purposes of attack. 

  • A state or act of deceit. 

treason

noun
  • An act of treachery, betrayal of trust or confidence. 

  • The crime of betraying one’s own country. 

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