GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
U-Boats were pretty much as far as they got.Were the German's a real threat to the US? Europe, yes, but the US? I doubt it. How would they have ever attacked the US in a manner that would threaten its security or existence?
Even if Britain did get over-run by Germany, removing the Royal Navy from the Atlantic, the Kreigsmarine would still have to get past the U.S. Navy.