liberate vs pull back

liberate

verb
  • To release from slavery: to manumit. 

  • To release from chemical bonds or solutions. 

  • To acquire from an enemy during wartime, used especially of cities, regions, and other population centers. 

  • To release from servitude or unjust rule. 

  • To release from restraint or inhibition. 

  • To acquire from another by theft or force: to steal, to rob. 

pull back

verb
  • To retreat. 

  • To pass (the ball) into a position further from the attacking goal line. 

  • Used other than figuratively or idiomatically: see pull, back. 

  • To score when the team is losing. 

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