air force vs soldiery

air force

noun
  • A branch of the military mainly devoted to air warfare, as opposed to (land) army and navy. 

  • A unit in the U.S. Air Force larger than a division but smaller than a command. 

soldiery

noun
  • The profession or skill of being a soldier. 

  • Soldiers considered as a group. 

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