rearguard vs refuge

rearguard

noun
  • The defence, collectively the defenders. 

  • The rearmost part of a force, especially a detachment of troops that protect the rear of a retreating force. 

refuge

noun
  • An expedient to secure protection or defence. 

  • A state of safety, protection or shelter. 

  • A refuge island. 

  • A place providing safety, protection or shelter. 

  • Something or someone turned to for safety or assistance; a recourse or resort. 

verb
  • To return to a place of shelter. 

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