cavalry vs troop horse

cavalry

noun
  • The military arm of service that fights while riding horses. 

  • Source of rescue, especially in an emergency. 

  • An individual unit of the cavalry arm of service. 

  • The branch of the military transported by fast light vehicles, also known as mechanized cavalry. 

troop horse

noun
  • A cavalry horse. 

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