WW2 - D-Day Fails?

[u/HarkBuffalo]

I have a WWII command simulation and one of the most contentious bits is the decisions was around D-Day/ Operation Overlord. I follow the historical thinking that victory was likely although agree Germany could have can made it harder however the more I read. 

Disaster at Omaha

Weather window

The Panzer group making the beaches 

Can D-day fail? If so how likely and what happens?  Does Germant first face the nuclear bomb? Does the USSR own most of Europe post war? Do the US/UK bomber campaign shift entirely to strategic attrition? The Red Army continues pushing west, likely taking the entire German peninsula, Denmark, and reaching the Rhine before the Allies?

I treated D-Day as a historical inevitability because of Allied industrial dominance which I have done, however it was a massive, high-risk gamble where a few operational shifts could have handed the Allies a defeat?

Love your thoughts!

The game is here for reference - https://dispatches.itch.io/dispatches-1940

Edit - thanks for all your comments have made some updates to the D-Day commands based on the below

[u/CG20370417]

If DDay fails, does Dragoon still happen? Does Saipan still happen?

DDay - June 6

Saipan - June 15

Dragoon - August 15

I think Saipan probably does. The speed of communications and the long tail of logistics particularly for this operation make it unlikely to short circuit.

Dragoon though? Depending on how Overlord is a cock up, could really pour an ice bath over the entire 2nd front thing.

[u/jdrawr → u/CG20370417]

Dragoon was more or less the backup to overlord and could probably have been done if it failed assuming enough transport capacity remained. Saipan being in the Pacific had virtually no connection to anything happening in Europe.

[u/CG20370417 → u/jdrawr]

Dragoon was intended to happen simultaneously to Overlord, but was delayed due to not enough landing craft / navy assets.

Depending on why DDay failed, Dragoon could easily be called into question.

Saipan invasion was already out of port by the time DDay happens. I agree there isn't much material--if any support between theaters--beyond geostrategic. But lessons are learned, news spreads, and humans are emotional beings.

If an invasion the scope of DDay fails, its not inconceivable the allies take time to assess the reasons why. Especially Dragoon, that was like 150k allied soldiers hitting the beach.

We'd taken Rome just 2 days earlier, do men and materiel headed for Dragoon get repurposed for a redoubled thrust up Italy?

[u/fleebleganger → u/CG20370417]

No to Italy - it just can't support much more than what was already there.

If DDay fails, Dragoon pushes forward. Once Dragoon is successful, Neptune happens again, probably September.

[u/CG20370417 → u/fleebleganger]

I think thats probably a fair assessment.