Holding France is possible. At normal, exp + 0, I get a few corps to defend the Italian front and thats all it takes. Mountain entrenchment is especially useful here. For Germany, you shuttle every allied unit possible to the defense of France and make sure you have one French HQ and one British. For the most part, just retrengthen your forces when attacked, but if an oppurtunity presents itself kill off a German unit or two. This slows them down for a while. Also, move your entire navy off the coast of the low countries. This is useful both for hiting German troops on the coast and providing targets for their fighters. Gamey, I know, but it works. Finally, once USA joins, so when they enter, take everything over to Framce and buy an HQ asap. Hopefully, Paris will still be protected when USSR goes to war. Then the war will dramatically turn in your favor. In a game where I employed that strategy, The Russians were in Berlin in early '43, and the Western Allies were charging down Italy. I payed a heavy price in terms of navy and land forces for the Allies, but the Russians just overwhelmed Germany, since they were wasting all their money on France.