cannonade vs open fire

cannonade

verb
  • To discharge artillery fire upon. 

noun
  • A loud noise like a cannonade; a booming. 

  • The firing of artillery for a length of time. 

open fire

verb
  • To begin firing (weapons) at something or someone. 

noun
  • An uncovered fire. 

How often have the words cannonade and open fire occurred in a corpus of books? (source: Google Ngram Viewer )