aggression vs encroachment

aggression

noun
  • Hostile or destructive behavior or actions. 

  • The practice or habit of launching attacks. 

  • The act of initiating hostilities or invasion. 

encroachment

noun
  • An intrusion upon another's possessions or rights; infringement. 

  • That which is gained by such unlawful intrusion. 

  • An unlawful diminution of the possessions of another. 

  • An entry into a place or area that was previously uncommon; an advance beyond former borders; intrusion; incursion. 

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