leadership vs overlordship

leadership

noun
  • The office or status of a leader. 

  • The capacity of someone to lead others. 

  • A group of leaders. 

overlordship

noun
  • The position or quality of being an overlord. 

  • The realm of overlords. 

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