pioneer vs sapper

pioneer

noun
  • A person or other entity who is first or among the earliest in any field of inquiry, enterprise, or progress. 

  • A member of a children’s organization operated by the Communist Party, typically in the second of three stages toward becoming an member of the Party itself. 

  • One who goes before, as into the wilderness, preparing the way for others to follow. 

  • Some people will consider their national heroes to be pioneers of civilization. 

  • A member of any of several European organizations advocating abstinence from alcohol. 

verb
  • To be the first to do or achieve (something), preparing the way for others to follow. 

sapper

noun
  • An officer or private of the Royal Engineers. 

  • Historical term for a combat engineer that is still used in some armies, in other words an engineer or a soldier engaged in attacking, destroying, and circumventing or building fortifications, bridges, and roads; a military engineer active in a combat zone. 

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