concordat vs truce

concordat

noun
  • A formal agreement between two parties, especially between a church and a state; specifically, an agreement between the Pope and a government. 

truce

noun
  • an agreement between opposed parties in which they pledge to cease fighting for a limited time 

  • a period of time in which no fighting takes place due to an agreement between the opposed parties 

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