infantry vs militia

infantry

noun
  • The part of an army consisting of infantry soldiers, especially opposed to mounted and technical troops 

  • A regiment of infantry 

  • Soldiers who fight on foot (on land), as opposed to cavalry and other mounted units, regardless of external transport (e.g. airborne). 

militia

noun
  • An army of trained civilians, which may be an official reserve army, called upon in time of need, the entire able-bodied population of a state which may also be called upon, or a private force not under government control. 

  • Synonym of militsia: the national police force of certain countries (e.g. Belarus). 

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