Gen. Dwight D. Eisenhower gave a speech to U.S. soldiers on June 5, 1944, the day before the invasion of Normandy. (Eisenhower Presidential Library)

On this day 73 years ago, the Allied Expeditionary Forces, under the overall command of Gen. Dwight D. Eisenhower, descended on the shores of Normandy, France, and helped pave the way for the end of World War II.

About 156,000 soldiers, at least 4,000 ships and 11,000 airplanes invaded Nazi-controlled Western Europe in a massive and coordinated attack called Operation Overlord. Now commonly known as D-Day, it turned the tide against Adolf Hitler and Nazi Germany. Its success, albeit bloody, defined not only the future of the world, but also the legacy of the military leader who would later become the 34th president of the United States.

The Washington Post spoke with Keith Huxen, senior director of research and history at the National WWII Museum in New Orleans, to get a better understanding of what it was like to be in Eisenhower’s shoes in the days that would later define his career.

Behind D-Day’s success was an overworked man who carried the weight of the world on his shoulders and expected the worst.

How much weight did D-Day place on Eisenhower? What was he like in the days and hours leading up to the launch of the Allied Forces?

He was nervous. He was very tense. This was something he’d worked almost nonstop for months at a time. He knew that this entire enterprise rested on his shoulders. Eisenhower had been living on a diet of coffee and cigarettes. He’d been smoking four packs a day. He had some health issues. His blood pressure had risen to very high levels.

Eisenhower, after giving the order to finally go on the morning of June 5, went back to — he had a trailer where he was resting on the grounds (at Southwick House in southern England). He wrote out a note that became famous later on.

In this note, he stated that he imagined the landings had failed. He wrote that this was not the fault of all these troops that were underneath him. It’s really a remarkable moment when you think about it. He was considering everything that might go wrong. Now it was out of his hands. He had to put trust into the faith of his commanders and troops to carry out the plan. … He did not want them to be blamed for it. That tells you something about his character.

The note read:

“Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops.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 upon 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.”

(Eisenhower accidentally dated the letter July 5 instead of June 5. He tucked it in his wallet. An aide later found it and decided to keep it.)

Eisenhower wrestled with the idea of postponing Operation Overlord. Why?

The invasion was originally scheduled to launch in the morning of June 5. It was postponed for 24 hours because of bad weather. … This was a very intricate invasion, lots of things happened in sequences. It’s nothing that you can just pull back at the starting gate. It’s not something you can keep secret. We’d been fortunate, and lucky in some way, that we managed to maintain secrecy. The Germans knew we were coming; they just didn’t know where and when.

(Eisenhower) made the call to postpone for 24 hours. He only had a three-day window. His weather caster told him, “You have a three-day window with the weather where we can launch the invasion.” The next day, the weather had calmed down enough. He made the decision (to move forward) at about 4:30 in the morning on June 5. … The troops hit the beaches 24 hours later, at 6:30 a.m.

Eisenhower gave a speech to his soldiers. What was going through his mind as he was writing that speech?

He was trying to encourage them. He was trying to put them in a frame of mind that they can do this, encouraging them to be successful. … He knew that a lot of these young men won’t be coming back. He was thinking about his troops and what a burden it was to have to order men to their death. They knew it, too. But they were young men and younger men tend to be cocky and think it’s not going to happen to them and it’s going to happen to the other guy. He’s trying to give them a sense of purpose by pointing out that this is going to liberate people living under the oppression of Nazi Germany.

The speech read, in part:

“Your task will not be an easy one. Your enemy is well trained, well equipped and battle-hardened. He will fight savagely. … I have full confidence in your courage, devotion to duty and skill in  battle. We will accept nothing less than full Victory!”

How did the letter resonate among his soldiers and around the country?

It had the desired effect. People understood the context of what we’re fighting for. In 1944, when this happened, outside of some high levels of government … the American public was ignorant of the true nature of Hitler’s regime. The first concentration camps were not liberated until January 1945. People today already know about the worst aspects of World War II and understand the moral significance of what’s at stake. That’s not the case when this operation was going on in 1944. The real discovery of the concentration camps that today gives a moral meaning to the defeat of Nazi Germany and why it was so important for the allies to win World War II was not public knowledge in the summer of 1944. That was still six months in the future before we started to liberate those concentration camps.

What did the success of the Normandy invasion mean for the United States, its allies and Eisenhower?

Dwight Eisenhower was the supreme commander of the invasion of Normandy, that was for the Americans and the British and the Soviets, their fates hang in the balance. It’s the moment that we had to win if we were going to win World War II. We had to have that battle. If Hitler succeeded in pushing us back into the ocean, it would’ve been years before we could’ve mounted a military invasion like that again. And the likelihood of political support in the U.S. and Britain would’ve melted away in those years. Hitler would’ve maintained his power and continued on with his murderous policies.

It’s a defining moment of World War II. It made Eisenhower’s reputation. It was the basis, I believe, of his reputation leading up to the American presidency. I don’t think he would’ve been president had he not been the supreme commander of Normandy.

Read more:

D-Day shaped America’s role in the world

D-Day at 70: Historic photos from the invasion of Normandy

How Eisenhower worked stealthily to rein in Joseph McCarthy