smokescreen vs stratagem

smokescreen

noun
  • Smoke used as a disguise, mask or cover, as of troops in battle. 

  • Anything used metaphorically to conceal or distract. 

stratagem

noun
  • Military deception or artifice. 

  • Cunning and artifice in general. 

  • A tactic or artifice designed to gain the upper hand, especially one involving underhanded dealings or deception. 

  • Specifically, such a tactic or artifice in military operation. 

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