invasion vs liberation

invasion

noun
  • A military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of conquering territory or altering the established government. 

  • The breaching of the skin barrier. 

  • The spread of cancer cells, bacteries and such to the organism. 

  • The entry without consent of an individual or group into an area where they are not wanted. 

liberation

noun
  • The act of liberating or the state of being liberated. 

  • The achievement of equal rights and status. 

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