corps vs regiment

corps

noun
  • A battlefield formation composed of two or more divisions. 

  • An organized group of people united by a common purpose. 

regiment

noun
  • A unit of armed troops under the command of an officer, and consisting of several smaller units; now specifically, usually composed of two or more battalions. 

verb
  • To systematize, or put in rigid order. 

  • To form soldiers into a regiment. 

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