combat engineer vs trooper

combat engineer

noun
  • A soldier employed to carry out engineering tasks in support of land forces during combat operations, facilitating the mobility of friendly forces while impeding that of the enemy; traditionally and often still today called a sapper. 

trooper

noun
  • A soldier. 

  • One who endures adversity or hardship with an attitude of stoicism and persistence. 

  • A cavalry horse; a charger. 

  • A mounted policeman. 

  • A soldier of private rank in cavalry or armour. 

  • A troopship. 

verb
  • To work steadily at an unpleasant job without complaint. 

  • To work as a trooper. 

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