enchain vs unite

enchain

verb
  • To link together. 

  • To restrain with, or as if with, chains. 

unite

verb
  • To bring together as one. 

  • To come together as one. 

noun
  • A British gold coin worth 20 shillings, first produced during the reign of King James I, and bearing a legend indicating the king's intention of uniting the kingdoms of England and Scotland. 

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