Thomas Keightley 
Secret Societies of the Middle Ages [EPUB ebook] 
The Assassins — The Knights Templars — Secret Tribunals of Westphalia

The present volume is devoted to the history of three celebrated societies which flourished during the middle ages, and of which, as far as we know, no full and satisfactory account is to be found in English literature. These are the Assassins, or Ismailites, of the East, whose name has become in all the languages of Europe synonymous with murderer, who were a secret society, and of whom we have in general such vague and indistinct conceptions; the military order of the Knights Templars, who were most barbarously persecuted under the pretext of their holding a secret doctrine, and against whom the charge has been renewed at the present day; and, finally, the Secret Tribunals of Westphalia, in Germany, concerning which all our information has hitherto been derived from the incorrect statements of dramatists and romancers.