On the eve of D-Day, Gen. Dwight David Eisenhower paid a visit to the Airborne Infantry – a commander about to send warriors into battle. His presence, according to his grandson, David, said to them, "'Whatever happens tonight ... your sacrifice will be meaningful.' He loved these soldiers and he just wanted to see them."

David Eisenhower's grandfather commanded the greatest military operation of history's most terrible war. David grew up on the Eisenhower farm at Gettysburg, just over the hill from the scene of the greatest battle of the American Civil War. As president, Ike named the presidential retreat Camp David after his grandson. 

They were close – but not close enough to share memories of D-Day. "He did not tell stories," David said. "In fact, I was discouraged from really raising the subject with him. World War II was not that safe a topic."

Because? "This would apply to Franklin Roosevelt and everybody in command responsibility. Winston Churchill as well. They said their piece in memoirs. They said it the way they wanted to say it. I think that they felt that every decision that they made in World War II carried consequences."

"So, the decisions were too consequential to be the subject of small talk?"

"That about distills it. The lives of literally millions in Europe were at stake."

David did not learn about D-Day sitting at his grandfather's knee; he learned about it researching and writing "Eisenhower at War," which was a finalist for the Pulitzer Prize. "He did not have a grandiose notion about his position in the war. He was part of something much larger than himself, and he understood that," he said.

President Roosevelt named Eisenhower commander of the operation code-named "Overlord" in December 1943, just six months before troops were supposed to go ashore at Normandy. There was a plan in place; but it was up to Ike to make sure the plan would actually work.

"The initial assault was three divisions, with two following up, meaning a five-division Overlord," David said. "He wanted 12 divisions. So, he expands the landing, doubles it. Better than doubles it."

Seven thousand ships and 2.8 million men were assembled for the invasion and the follow-on landings. There were too many decisions for any one man to make, but one decision only Ike could make: When to launch.

Martin asked, "What are the factors he has to consider in making that go/no-go decision?"

"The overriding factor is the safety of the landing, and that is a combination, it seems to me, of weather and the pace of German reinforcement," said David Eisenhower. 

One of the few times Eisenhower ever spoke about D-Day was with Walter Cronkite on the 20th anniversary in 1964. They visited the command post, where Gen. Eisenhower had been given the weather forecast for June 5th. "We came down here hoping and praying that the weather would be sufficiently good," he recalled. Instead, he was given "the worst report you ever saw. He talked about gales hitting the Normandy beaches and winds up to the rate of 45 miles per hour, that kind of thing. The landing would be impossible."