appeasement vs palliation

appeasement

noun
  • The state of being appeased; the policy of giving in to demands in order to preserve the peace. 

palliation

noun
  • Extenuation; mitigation. 

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

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