There were 36,525 days in the 20th century. Of these, none was more consequential than June 6, 1944.

D-Day, the Allied invasion of Normandy in Nazi-occupied France. It did not end World War II,

but without it the Nazi war machine would not and could not have been defeated.

We of course know the good guys, America, England and its allies won, but in 1944 there was no certainty of success.

In fact there was just as much doubt as confidence. Winston Churchill's senior advisor Field Marshal Brooke wrote in his diary,

I am very uneasy about the whole operation. It may well be the most ghastly disaster of the whole war.

Brooke's fears were entirely reasonable. First, there were tens of thousands of men,

and millions of tons of material and supplies that had to be moved 100 miles across one of the roughest bodies of water in the world, the English Channel, and it had to be kept secret.

If the Germans knew where and when the Allies were landing, they could mass forces against them and turn the beaches of northern France into killing fields.

To prevent this the Allies took every possible precaution. The Air Forces destroyed bridges, roads and railways that might be used by the Germans to rush troops to the invasion site.

Everyone knew the attack was coming, the key was to keep the Germans guessing.

Fake radio chatter was broadcast to suggest the beaches near Calais would be the landing point.

Double agents leaked fake details of units forming in southeast England, and movie set designers built phony tanks,

planes and ships to support the ruse of an army preparing to cross near Dover for the benefit of German reconnaissance pilots and spies.

The Germans swallowed it all. But the Nazis were not the only enemy the Allied forces faced.

Mother Nature was just as threatening. The 23,000 power troopers in Gliderborne infantry jumping into Normandy needed moderate winds to be effective.

The 12,000 Allied aircraft needed clear skies. The invasion fleet of 6,000 vessels needed calm seas, and had to be a low tide to expose Nazi obstacles and mines.

When high winds and rain began pummeling the channel, Allied Supreme Commander General Dwight Eisenhower postponed the invasion date of June 5th by 24 hours.

That might not sound like a significant delay, but it was. All forces were concentrated and ready to go. All the plans, all the deceptions could be exposed at any moment.

Then came a new forecast. The weather appeared to be breaking. There might be a 12 hour window of opportunity. Eisenhower gave the order. We go.

Immediately the greatest invasion fleet ever assembled set sail on board were over 130,000 young soldiers.

Consider for a moment who these soldiers were. The average age of the American GIs was 21, most had never seen combat or even been 50 miles from their hometown.

...