Some things to remember about D-Day
Eisenhower had written an in case of failure letter. There were so many factors that the Allies were pretty prepared for failure and withdraw.
Quote:
BY Lucas Reilly

Getty Images
General Dwight D. Eisenhower sounded confident before the Normandy Invasion. “This operation is planned as a victory, and that’s the way it’s going to be. We’re going down there, and we’re throwing everything we have into it, and we’re going to make it a success,” he said.
Operation Overlord was a massive campaign—an invasion of 4,000 ships, 11,000 planes, and nearly three million men—that was launched on June 6, 1944. Despite a year of strategizing and a boatload of confidence, Eisenhower had a quiet plan in case his mission failed. If the armada couldn’t cross the English Channel, he’d order a full retreat. One day before the invasion, he prepared a brief statement just in case:
"Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based on the best information available. The troops, the air and the Navy did all that bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone."
|
Logically everything says that this invasion should have failed. Storming beaches, especially in this scale required nearly everything to go right, even with the success of diversionary tactics such as the inflatable army (operation Fortitude), there were still a lot of things that went incredibly wrong such as targeting and air support.
As well the Germans were incredibly well dug in, their fortifications and firing positions should have allowed the German's to hold the beaches long enough for re-enforcement.
However the question of what saved the day could be summed up with the simple statement of Hitler's sleeping habits.
Hitler liked to stay up late and watch movies and then sleep in later. Because of this and the amount of fear for waking up the Fuhrer with bad news.
When we watch old war movies, we always see this incredibly competent German War machine with spies everywhere. But the truth of the matter is that German Intelligence and especially Abwehr were fairly incompetent and compromised by the fear of giving Hitler bad news, so they were completely fooled and because of that the high command believed that the Normandy Invansion was a distraction from the real invasion at Pas De Calais. So even though Rommel was screaming for permission to move his re-enforcements of
three Panzer divisions, with another 6 that could be bought in over time. But because nobody believed that this was the real invasion, and nobody wanted to wake Hitler up with the bad news that they were wrong about the real axis of attack, those formations weren't moved until it was too late.
the Allies were able to wear down the German beach positions at murderous cost and a foothold was establish.
the question remains, what would have happened if Rommel had been allowed to enforce Normandy with 9 Panzer divsion? The allies might have gotten off of the beach, but they would have run into an absolutely fierce counter attack before the could establish a full army in the field with logistical backing.
However there was another problem that worried Rommel. the Luftwaffe and German Navy were pretty much non entities at the time. The Navy wasn't really a factor in the Second World war with the exception of the Submarine force. The Luftwaffe had been withdrawn from the Normandy area had basically been withdrawn to protect Berlin. "For want of a nail".
Two major mistakes compounded by a bunch of little mistakes lead to the German defeat on D-Day.
Interesting look at how close D-Day came to failure
http://www.bbc.co.uk/guides/zgtttfr
John Keegan scenario on if D-Day had failed.
http://www.npr.org/templates/story/s...ryId=105064196