commissioning vs enlistment

commissioning

noun
  • The process of assuring that all systems and components of a major piece of equipment, a process, a building or similar are designed, installed and tested according to the operational requirements of the owner or final client. 

enlistment

noun
  • The act of enlisting. 

  • Voluntary service based on an individual's desire to serve a cause. 

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