Here's my scenario:
Excuse me for being "unrealistic", but I think that all of the world could have been decimated and conquered by Germany, even before Christmas of '38. How would they do it, you ask?

Meet the F-16 Fighting Falcon.
It's pretty much just a Spitfire with jets taped on the back, right?

Meet the M1A1 Abrams.
It's pretty much just a jeep with some metal and guns, right?
And this is how Germany could of conquered the world. Discuss.