ambush vs flush out

ambush

verb
  • To attack by ambush; to waylay. 

  • To station in ambush with a view to surprise an enemy. 

noun
  • The act of concealing oneself and lying in wait to attack by surprise. 

  • The concealed position or state from which a surprise attack is launched. 

  • An attack launched from a concealed position. 

  • The troops posted in a concealed place, for attacking by surprise; those who lie in wait. 

flush out

verb
  • To drive out or expose something or someone, as a game bird or other game animal from cover. 

  • To flesh out. 

  • Used other than figuratively or idiomatically: see flush, out. 

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