When Shakespeare returned to English history as a subject for plays, he reopened his copy of Raphael Holinshed's Chronicles. But the historical account of Richard II is very complicated and Shakespeare had to simplify it in the extreme to make it fit into a two to three hour drama. You may well have never heard of Raphael Holinshed, but he was Elizabethan England's favorite historian. Shakespeare probably used the 1587 edition of Chronicles, published just five or six years before he began Richard II. Thus for the Elizabethan audience, which had not had the time to read the book, Shakespeare put it on the stage! As I said, he simplified and dramatized the events. For instance, the Queen had a much larger role in the play than the book. Historically, the Queen Isabella, was only eleven years old, but here we see her as a mature and astute adult.