hang up one's boots vs stand down

hang up one's boots

verb
  • retire, call it a day 

stand down

verb
  • To withdraw or retire from a position or from a team. 

  • To wait; to stop pursuing, stop fighting, or relax from a heightened readiness posture. 

How often have the words hang up one's boots and stand down occurred in a corpus of books? (source: Google Ngram Viewer )