palliation vs peace offering

palliation

noun
  • Extenuation; mitigation. 

  • The alleviation of a disease's symptoms without a cure; temporary relief. 

peace offering

noun
  • A religious sacrifice. 

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

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