thenceforth vs thereupon

thenceforth

adv
  • From that time on. 

thereupon

adv
  • Upon that; thereon. 

  • In consequence, or by reason, of that; therefore. 

  • Following that; forthwith; in sequence, but not necessarily in consequence. 

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