There are a lot of ways that the battle of D-Day could have failed for the Allies. And, part of the American victory was because of both a lucky guess on the part of our weather forecastor and also the successful deception of the Allies against the Axis as to where and when.
So the question is, if the d-day invasion had failed, would things have gone? there are videos that give an answer to this on youtube but there are several different possible answers!
One is claiming communist control over all of Germany and/or France cause the brit and americans were not around! But there are other possibilities.
Lets suppose that God helped the USA and UK have an invasion that worked out and that it could have failed and gone disastrously wrong. What would have been the other possible likely results? Communism rules all of Europe for 50 years or something else entirely?