stand by vs stand down

stand by

verb
  • To wait in expectation of some event; to be ready. 

  • To support; to continue to support despite things being bad. 

  • To remain loyal or faithful to. 

  • To do nothing. To be inactive in a situation. 

stand down

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

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

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