Wonderful, interesting article!! But I think you make a mistake in excluding the aim of defeating Nazi Germany completely. Perhaps putting the Soviet Union at a disadvantage through D-day could have been an aspect of conducting the operation. But if anything, it was a mere side item. D-day was all about the liberation France and the ensuing liberation of other European nations. And, this is just speculation on my part, but I think the reason why the Allies, especially the Americans, slowly ate away at the Nazi grip on the Western Front, including Italy and Africa, was that they believed it to be impractical to invade mainland France when German reserves in Italy and Africa could reinforce their brothers in arms (which (German reserves)would have been available if we were to go straight for France)in Normandy. I believe all the Allied commanders saw that the best way to defeat the Nazi grip on western civilization, what grip they did have, was to slowly eat through it, like termites through wood.