It comes from this book, which I have in paperback, but see now it's also available by Kindle.
Thanks! I'm going to look into getting it (prefer paper to electrons for things like this). I think I may have spotted it on the shelf of my local used bookstore last week (they had Bruce Catton's Army of the Potomac trilogy that I bought instead of the other books I was looking at).
But, for whatever my opinion might be worth: it's a great book, and I think you'll finish it with a higher respect for Robert E. Lee as a general than the common view of his performance at Gettysburg would lead one to expect.
I've never really thought that the common view of Lee's performance at Gettysburg did him enough credit. There were a heck of a lot of mistakes to spread around on both sides of Emmitsburg Pike. One book I really enjoyed on the subject was
"Lost Triumph" by Tom Carhart that, albeit relying on a lot of circumstantial evidence, claims that Lee really did have a winnable plan for the third day. If you haven't read it yet, I'd highly recommend it.
Not trying to hijack the thread here, but I just went out to Amazon to look for a book a friend recommended (WWII) and the first two books that popped up in the advert section were Last Chance for Victory and Lost Triumph.
Considering that I hadn’t actually looked for either book on Amazon, it shows how stuff we all write here gets caught up in the great internet tracking matrix ...