Sir Alistair Horne, like that other great knight of military history, Sir Michael Howard, served in the Coldstream Guards during the second world war. According to Clausewitz (in Vom Kriege), his judgment will therefore be invested with insight denied to those who have never been shot over:

As long as we have no personal knowledge of war, we cannot conceive where those difficulties lie of which so much is said, and what that genius and those extraordinary mental powers required in a general have really to do.