tergiversate vs turn one's coat

tergiversate

verb
  • To change sides or affiliation; to apostatize. 

  • To evade, to equivocate using subterfuge; to obfuscate in a deliberate manner. 

  • To flee by turning one's back. 

turn one's coat

verb
  • To turn against a previous affiliation or allegiance. 

  • Used other than figuratively or idiomatically: see turn, coat. 

How often have the words tergiversate and turn one's coat occurred in a corpus of books? (source: Google Ngram Viewer )