ensign vs first lieutenant

ensign

noun
  • The lowest grade of commissioned officer in the United States Navy, junior to a lieutenant junior grade. 

  • A junior commissioned officer in the 18th and 19th centuries whose duty was to carry the unit's ensign. 

  • A badge of office, rank, or power. 

  • The principal flag or banner flown by a ship (usually at the stern) to indicate nationality. 

  • A flag or banner carried by military units; a standard or color/colour. 

  • Any prominent flag or banner. 

verb
  • To distinguish by a mark or ornament. 

  • To distinguish by an ornament, especially by a crown. 

first lieutenant

noun
  • The second lowest rank of a commissioned officer in the United States Army, Air Force, or Marine Corps, ranking above a second lieutenant and below a captain. The rank of first lieutenant is equivalent to the naval rank of lieutenant junior grade. 

  • An equivalent rank in other military forces. 

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