Kent Masterson Brown was on the Pennsylvania access equivalent of CSPAN's BookNotes, talking about his Retreat from Gettysburg, which I still haven't finished, having gotten somewhat distracted.
He repeated some of the stuff in the book about Lee & von Clausewitz, analysizing Lee's strategy and behaviour during the retreat by von Clausewitz's recipe. Given that we're fairly certain that Lee never read von Clausewitz, and we're also positive that he *did* read Jomini, this line of analysis is kind of peculiar. Lee might have arrived at von Clausewitzian conclusions independantly in the specific case of "retreat after a decisive tactical defeat", in a case of convergent evolution of theory, but we're pretty clear on Lee's grounding in theory at this point, I think. He was a Jominian. Hell, during the Civil War, von Clausewitz wasn't even a model for any major figure that I'm aware of - maybe one of the "Dutch" generals had read him, I suppose. The rival theoretician during the actual fighting-period was Mahan, not von Clausewitz. The older generation had trained under Jominian principles, the younger under Mahan's revisions.
Talking about theory in the field is probably a bit over-analytical, anyways. Lee was thirty years away from his schooling by the time of Gettysburg, and had been in the field for over a year. He was as far from theory as you can get and not be dead of wounds. By the time of Gettysburg, Lee's behaviour would have been influenced only by the lingering training and mind-set development aspects of theory, with his behaviour emerging more directly out of praxis and experience at that point.
I suppose you could say that the von Clausewitzian analysis proves its superiority over Jominian theory in predictive terms. A brilliant and active general's practical behaviour after a decisive defeat more closely resembles von Clausewitz's descriptions of successful retreat than it does Jomini's version. Given the rather low repute which Jomini's work now has in retrospect, that's entirely plausible. I wonder what, if anything, Mahan had to say on the subject?
Incidentally, Brown mentioned that he's working on a book on the 1862 Maryland campaign. I'd be excited, except in the same breath he stated that it's one of four books that he's working on in tandem, all in his spare time. Given that Retreat from Gettysburg apparently took twenty years of part-time research, I'm not sanguine that I'll see his logistical treatment of Antietam before 2024 at the earliest.