guidon vs second lieutenant

guidon

noun
  • A small pennant or banner carried by infantry soldiers to direct troop movement. 

  • A soldier assigned to carry such a banner. 

second lieutenant

noun
  • The lowest rank of a commissioned army officer, below a lieutenant. 

  • The lowest rank of a commissioned officer in the United States Army, United States Air Force, or United States Marine Corps, below a first lieutenant. The rank of second lieutenant is equivalent to the naval rank of ensign. 

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