peace offering vs sweetening

peace offering

noun
  • An offering or concession made to an adversary in the hope of obtaining peace or reconciliation; an olive branch. 

  • A religious sacrifice. 

sweetening

noun
  • The process of making something sweeter. 

  • A sweetener. 

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