Now, we've got to remember had a nifty sense of humour that could have won any country over!
But I don't think the Wehrmacht could have taken Russia, 'cause they weren't equipped for Russian climates. He could perhaps have taken Britain, but could he have held it? Not likely, IMO. He needed 400,000 soldiers in Norway (that's more soldiers than there were inhabitants in the capitol) to pacify the southern parts.