about-face vs turn back

about-face

verb
  • To turn 180 degrees to face the opposite direction. 

  • To change opinion or attitude drastically. 

noun
  • A reversal in direction; a reversal of attitude or opinion. 

  • An abrupt turn to face the opposite direction. 

turn back

verb
  • To reverse direction and retrace one's steps. 

  • To cause to reverse direction and retrace one's steps. 

  • To return to a previous state of being. 

  • To prevent or refuse to allow passage or progress. 

  • To adjust to a previous setting. 

  • To fold something back; to fold down. 

How often have the words about-face and turn back occurred in a corpus of books? (source: Google Ngram Viewer )