countermand vs knock on the head

countermand

verb
  • To counteract, to act against, to frustrate. 

  • To recall a person or unit with such an order. 

  • To revoke (a former command); to cancel or rescind by giving an order contrary to one previously given. 

  • To cancel an order for (some specified goods). 

noun
  • An order to the contrary of a previous one. 

knock on the head

verb
  • To put an end to; to defeat or frustrate (a scheme or project). 

How often have the words countermand and knock on the head occurred in a corpus of books? (source: Google Ngram Viewer )