Mosby implies that Stuart was "thrown under the bus" in the official history by Lee's staff. In the book he goes into very vivid detail to prove that Stuart was were he was supposed to be, and Hill and Heth were off on a raid, when they were supposed to be concentrating on Lee at Cashtown Pass...and the story of the "spy" was fiction. So, when I read this, I think of the Movie "Gettysburg" and how it this was depicted.
David