dig in vs turn tail

dig in

verb
  • To dig trenches to resist an enemy attack. 

  • To cover over by digging. 

  • To adopt a resolute state of mind. 

  • To begin eating. 

  • To engage in a burst of hard work. 

turn tail

verb
  • To turn away from someone or something, in preparation for running away; to reverse direction; to leave or flee. 

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