When the D-Day forces landed, Hitler was asleep. None of his generals dared send re-enforcements without his permission, and also, no one dared wake him.
It's a day that determined the direction of history, signaling the downfall of Hitler's Germany.
But the Nazi leader could have been victorious, and the world would likely be a different and much nastier place if one seemingly ludicrous thing had been different.
His aides were too scared to wake him up.
Despite the overwhelming might of the combined forces of Russia, Britain, and the United States, the outcome of World War II was a close-run thing.
Germany's charismatic supreme commander had vehemently reserved the ultimate say on when and where any of his most elite military forces were to be committed in response to the invasion.
He was a fractious man known for temperamental outbursts and imposing instant demotions if displeased.
So, when the first urgent but confused reports of an Allied landing were radioed and rung through to the Wolf's Lair headquarters as early as 4 am on the morning of June 6, his staff found him asleep.
Nobody dared wake him.
Better to let the great man sleep and give him the most precise picture when he wakes. The confusion was rife and actively enhanced by a key double-agent in the pocket of the Allies, plus an intelligence campaign was severely misleading the Germans.
And, besides, the weather over Normandy had been forecast to be atrocious, leading many Germans to believe any action there was simply a feint and that the main attack would come northwards at the area around Calais.
"We don't know" was not an answer for the Fuhrer.
This simple hesitation by cowed staff may have cost Germany, if not victory, a tremendously advantageous negotiated peace.
It certainly gifted the Allies 12 vital hours.
Germany's reserve tanks and troops, which could have responded within minutes, sat and waited. The 10,000 border troops hiding in their pillboxes and trenches were left to hold the line alone as 175,000 Allied troops steadily waded ashore.