AMNA NAWAZ: As we have noted, today marks the 80th anniversary of D-Day.

And, for most, the Allied invasion of Normandy is an event in history.

But a new book transports us back eight decades ago, hearing directly from those who lived history.

Garrett Graff is the author.

And I spoke with him recently about "When the Sea Came Alive."

Garrett, welcome back to the "NewsHour."

Thanks for being here.

GARRETT GRAFF, Author, "When the Sea Came Alive: An Oral History of D-Day": It's a pleasure.

AMNA NAWAZ: So, this is now the work of 18 months that you spent assembling what's the largest, most comprehensive compendium of first-person testimonials from this historic day and event.

You have compiled oral histories before, like your wonderful book on 9/11, in particular.

Why did you think this format was necessary now for this story?

GARRETT GRAFF: This is a moment where we have, for all intents and purposes, every first-person memory that we are going to have of D-Day.

And so, for me, this was a moment to try to retell the story of D-Day in the voices of the participants themselves as this event slips from memory into history, and to try to make it come alive for a new generation that are not as familiar with the story of D-Day.

AMNA NAWAZ: "When the Sea Came Alive," tell me where that comes from and why you chose that as the title.

GARRETT GRAFF: So, the title actually comes from a German defender at Omaha Beach, and it's his reaction to waking up that morning in the bunker and looking out at what is all of a sudden to him this sea packed with the Allied ships as the invasion arrives off the coast of Normandy.

And I think to me what the title captures in some ways is the audacity of this operation.

This is, in many ways, I think the most audacious human endeavor we have ever seen and probably may ever see in the rest of history as well, a million Allied combatants on the move on D-Day, the largest armada in the history of the world, 7,000 ships crossing the channel overnight in -- completely surprising the Germans.

Right up until the last minute, the secrecy of this event holds.

AMNA NAWAZ: There are stories from voices who are forever etched in history, Churchill, Eisenhower, and the likes.

But, honestly, some of the most compelling lines and stories come from people whose names we have never heard of before.

There's Private 1st Class George Alex, who is a paratrooper, dropped into Normandy just six hours ahead of the invasion.

You quote him here in that moment, saying: "Yes, I was afraid.

I was 19 years old, and I was afraid."

And there's Sergeant Alan Anderson, and he shares this about preparing for the invasion.

He said -- quote - - "The Army was prepared to accept 100 percent casualties for the first 24 hours.

It was interesting that we all turned and looked at each other and said, well, it's tough that you have to go."

How did these men in the testimonials that you read from them think about their place in an operation of that kind of scale and scope, as you described?

GARRETT GRAFF: We look back and we view D-Day as this amazing, historic triumph of heroism and courage and bravery.

When you hear from the soldiers crossing the channel on the night of June 5, the paratroopers flying across the channel that night, there's not a lot of heroism or bravery or courage that they're feeling in that moment.

They're lonely.

They're scared.

They're wondering if they're going to make it through to the end of the next day.

AMNA NAWAZ: There's a story you tell about a man named Waverly Woodson Jr.

He was a Black medic on Omaha Beach.

Why is his story important here?

GARRETT GRAFF: Waverly Woodson is, to me, one of the most fascinating characters of this book.

He is a medic with the only Black combat unit that lands on D-Day and is wounded before he even gets to shore and spends 30 hours on Omaha Beach treating the wounded before he is evacuated himself.

He's one of what turns out to be a small handful of Black soldiers in World War II who are considered for the Medal of Honor, but amid the systemic racism of the segregated military in that moment, not a single Black soldier in World War II receives the Medal of Honor.

And it's only been this week for the 80th anniversary that he has been awarded a very long overdue Distinguished Service Cross, which is the nation's second highest award for combat valor.

AMNA NAWAZ: Garrett, it's also astonishing to weigh what this entire generation, the Greatest Generation, carried with them for 80 years and, in many cases, never talked about.

There's one line from a member of the 3rd Canadian Division, a Lieutenant Reg Weeks, who you quote in here.

He says: "The thing I remember is that the people who had not been killed, the people who had gone ashore ahead of me, there was a look in their eye which I have never seen repeated under any circumstances."

This is not a generation known for talking openly about this, right?

GARRETT GRAFF: When you go back through the history and the archives, so much of these oral histories were actually gathered between the 40th and the 50th anniversaries of D-Day, 1984, 1994, which was the moment that I think the nation, thanks in part to Ronald Reagan's famous speech at Pointe du Hoc in 1984, really reckoned with the legacy that this generation delivered for us, the way that these people, these 19-year-olds, these 21, 22-year-old sergeants leading them into battle saved democracy.

AMNA NAWAZ: There is a parallel a lot of people see between that time in history and what we're living through now.

Did you see any of those parallels through what you researched or did the people you talk to see that?

GARRETT GRAFF: Absolutely.

I thought a lot about, in researching and writing and editing this book, this modern moment, and both in terms of what's going on in Europe and the fight that Europe is in right now about the future of European democracy and then also our fight here at home.

And this is a year that we're going to spend a lot of this year talking about what America is and what it isn't.

And I think one of the ways that we can define that is what America is willing to fight for.

AMNA NAWAZ: The author is Garrett Graff.

The book is "When the Sea Came Alive: An Oral History of D-Day."

Garrett, thank you so much for being here.

GARRETT GRAFF: My pleasure.