chickenshit vs yellow back

chickenshit

noun
  • coward 

  • A low-ranking officer who lords over and needlessly makes life miserable for his underlings; a petty, abusive martinet. 

  • (A) petty and contemptible thing(s). 

adj
  • cowardly 

  • petty and contemptible; contemptibly unimportant. (Compare bullshit.) 

yellow back

noun
  • A coward. 

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