bowstring vs put before a firing squad

bowstring

verb

  • To strangle with a bowstring. 

noun

  • The string of an archer's bow. 

  • The string of an archer's bow, as used by the Turks for strangling offenders. 

put before a firing squad

How often have the words bowstring and put before a firing squad occurred in a corpus of books? (source: Google Ngram Viewer )