Watching Ronald Reagan read a baby boomer’s letter about her dad’s D-Day memories was the most emotional moment of my career.

It’s hard to imagine what the world might be like today had the Germans repelled the Normandy invasion 60 years ago.

Would a stalemate have followed, and then eventually a settlement that left Adolph Hitler in power?

Or would the Red Army have defeated the Nazis itself, but then kept all of Germany, and perhaps even France, after the war?

Would German scientists have beaten the good guys to developing the atomic bomb?

We don’t know because of men like Peter Robert Zanatta. Through his daughter’s memory, he became D-Day’s human face to me.

Zanatta was a first-generation Italian immigrant whose parents moved from rural Idaho to California during the Great Depression to get enough to eat.

He wasn’t unique, just one of millions who answered the call. But he and they were special.

Zanatta could just as easily have been a Chicago Pole, a Brooklyn Jew, a Georgia Cracker, a New England WASP or a Tuskegee airman. It was the era of shared sacrifice.

Watching TV pictures of Lisa Zanatta Henn weeping as Reagan told her father’s story in 1984 forever burned into my mind the debt all of us owe today.

The invasion, Lisa said, was the “single biggest experience of his life. He loved my mom and us kids, but he never forgot D-Day.”

As a child her dad told her, “Someday, Lis, I’ll go back. I’ll go back and I’ll see it all again. I’ll see the beach, the barricades and the graves.”

He never made it, though. He died from cancer in 1976, months before a planned Normandy trip.

“He would say those words hundreds and hundreds of times for as long as I can remember. When he said them, he always looked like he was somewhere else, remembering something painful, yet something he was so proud of.”

Eight years after his death, she decided to honor him by attending the 40th anniversary commemoration of D-Day.

Lisa, then and now a Pleasanton, Calif., United Airlines flight attendant, grew up understanding just how lucky her dad was to be in the first wave on Omaha Beach and live to tell the tale of it.

His stories made the D-Day anniversary a family occasion — not a holiday but more of a solemn remembrance.

“Not many people may know or even care about this day, but I always will–I can’t remember when it wasn’t important to me.”

“June 6th is a special day in my family’s house. … Maybe he made it too big a thing in his life. Maybe my family and I hang on to this part of my father’s life and make more of it than it was. I’ve tried to make my friends understand what I feel, but they all look at me like I am kind of strange. … But it was, and always will be, a big event.

“It changed everyone’s lives — then and now. Everyone takes it for granted. Maybe that’s what made my dad different. After he fought one of the most important battles in our nation’s history, he could never take anything for granted again.”

Lisa, who was there a decade ago for the 50th anniversary commemoration, didn’t go this time because it coincided with the high school graduation of one of her children.

But she had pledged to her father before he died that “I’m going there someday, Dad, and I’ll see the beaches and the barricades and the monuments. I’ll see the graves and I’ll put the flowers there just like you wanted to do. … I’ll never forget what you went through, Dad, nor will I let anyone else forget — and dad, I’ll always be proud.”

Lisa kept her promise, and we should do the same. Not necessarily by visiting the beaches, but by understanding how her father and millions of others made America what it is today.

When I was a child, my late father would talk about his World War II service. But not until I was older did I come to appreciate just what he and his generation did.

I once asked him why, at 36, a newly minted lawyer with a developing practice and a wife wanting a family, he became among America’s oldest and best-educated enlisted men, even though he was well, well past draft age.

It was simple, he said: His country had been attacked, and that was what you did.

His ability to speak several languages — but luckily for him not German or Japanese — led to his spending the war on the North Atlantic, boarding neutral merchant ships looking for spies and military cargo. He realized how much easier he had it than those who were at Normandy. After seeing “The Longest Day,” the Hollywood epic about D-Day, he got more than a little misty.

Those were the guys we really owe for stopping Hitler, he said. He could not comprehend what it must have been like storming the beaches, and neither can I today.

When NBC’s Tom Brokaw coined the phrase “The Greatest Generation” to describe Peter Robert Zanatta, Philip Brown and millions of their buddies, he got it exactly right.

Peter A. Brown is an editorial page columnist for the Orlando Sentinel.