Twenty Years After his own service to Mazarin, he refuses to watch over the Duc de Beaufort, who is imprisoned at the time, and soon learns that, in consequence, he is to be returned to the Bastille, though this does not deter him from speaking highly of the achievements of d'Artagnan and the Three Musketeers. Having determined that d'Artagnan is the man he seeks, Mazarin enters the chambers of the Queen to let her know that he has enlisted the man who had served her so well twenty years earlier. The Queen, feeling guilty for having forgotten d'Artagnan's service, gives Mazarin a diamond
The Twenty Years' Crisis be acknowledged as a starting point. He concludes his discussion by suggesting that "elegant superstructures" such as the League of Nations "must wait until some progress has been made in digging the foundations". Since its publication, "The Twenty Years' Crisis" has been an essential book in the study of international relations. It is still commonly read in undergraduate courses, and the book is considered "one of the founding texts of classical realism". The book has served as the inspiration for numerous other works, such as "The Eighty Years' Crisis", a book written by the International Studies Association as a survey