The 68th anniversary of the D-Day invasion of Normandy, France, is Wednesday, June 6, 2012.

After all the logic, after all the strategy, after all the tactics, after all the training, what matters is the individual, said Tonie Holt, who, upon retiring from the British Army, dedicated his life to studying battlefields and making them accessible to the masses.

I remember sitting alongside a returning G.I. on the cliffs where he had landed on D-Day 40 years earlier. He had been with the 16th Infantry Regiment and in the eye of the storm. He had been 18 years old on D-Day. Never in action before. It was just the two of us and he talked for some time. He started unknowingly, as all old soldiers do, with the 'memories' that he had recounted endless times at home. Partly truth, partly what he had read after the war, partly what he thought people wanted to hear. Then he stopped speaking. He took a deep breath and began to cry. I cried too. We were both on that beach in our minds, but his memory was real.

Between the sobs, Tonie continued, he told me what had happened -- men shot down all around him, the blood red color of the sea, the bodies in the waves, the noise, the chaos ... Eventually he was done. Over 40 years of suppressed memories had poured out in just a few minutes. As gently as I could I asked him, 'Why did you all go on after all that bloodshed?' He replied, 'It was a job that had to be done... That's it. You do what you have to do,' and we sat there in silence.

For Tonie, guiding people through dark histories has become his life's work. He and his wife Valmai pioneered the first modern commercial battlefield tour in 1978 and have spent the past 34 years leading tours and writing battlefield guides under the moniker Major and Mrs. Holt. The happily married couple release the sixth edition of their book D-Day: Normandy Landing Beaches Wednesday in honor of the 68th anniversary of the Allied invasion of Normandy, France, on June 6, 1944.

The World War II invasion under Operation Overlord was the largest seaborne invasion ever mounted, involving more than 850,000 troops crossing the English Channel from the United Kingdom to Normandy. The troops came from the United States, Canada, France, and the United Kingdom, and all fought Nazi Germany side-by-side along a 50-mile stretch of heavily fortified French coastline.

Gen. Dwight D. Eisenhower, the overall commander of Overlord, called the operation a crusade in which we will accept nothing less than full victory and by the day's end on June 6, the Allied forces gained a foothold in Normandy. More than 9,000 Allied soldiers lost their lives or were wounded in the first day, but more than 100,000 others began the march across Europe to defeat Adolf Hitler.

Visiting Normandy Today

The beaches of Normandy are now pilgrimage sites -- a treasure trove of history amidst a prosaic land.

The Normandy Landing Beaches are very nationality orientated, Tonie said. Most people first wish to visit the sites where their countrymen fought and, in so many tragic cases, died for our liberty.

The Holts said American visitors to Normandy should first see the little town of Sainte-Mere-Eglise where elements of Gen. James M. Gavin's 505th Parachute Infantry Regiment of the 82nd Airborne dropped during the night of June 5, eventually liberating the town from its German occupation:

They were one of many towns or villages in Normandy to claim 'first liberated.' The story is well told in the Airborne Museum, which features an historical C47, 'The Argonia.' An effigy of paratrooper John Steele hangs on the church spire, recreating the hours he spent dangling, playing dead, until the opposition was quelled. A hotel here is named after him.

The next stop, the Holts said, should be Utah Beach:

En route to the landing beach is the statue to Dick Winters of Easy Company, the heroes of 'Band of Brothers' fame. This fine memorial to leadership will be unveiled on June 6, 2012. Proceeding along the landing beaches, the next highlight is Pointe du Hoc. Here, Texan Col. James E. Rudder's Rangers dramatically scaled a forbidding cliff to take out the massive German defenses at the top of the cliff, notably the 144mm guns with a range of 25,000 yards pointing toward the incoming invasion force. When the Rangers laboriously reached the top, suffering many casualties, they found that the guns had been removed for repair to an orchard behind the cliff.

Bloody Omaha Beach, where the Pals Battalions of the National Guard saw wave after wave of their comrades slaughtered in front of them as they landed, would be a fitting next stop to pay respects. The Holts said the final unmissable site for American visitors is the Normandy American Cemetery, overlooking the wide sandy beach where many of the men fell. The site has an interpretative center that pays tribute to the historic invasion.

British visitors, the Holts said, tend to gravitate to the area of Pegasus Bridge in the small village of Benouville.

Here, Maj. John Howard of the 2nd Ox and Bucks Light Infantry landed by glider in a daring coup de main operation to take the vital bridge over the River Orne. The operation is well demonstrated in the Pegasus Memorial Museum, which has the original bridge in its grounds.

The Holts also recommend the British Cemetery and the Memorial in the old town of Bayeux, home of the historic Bayeux Tapestry that depicts the Norman Invasion of England in 1066.

Wherever you visit, Major and Mrs. Holt urged that a little bit of preparation will go a long way.

In the military we say 'Time spent in reconnaissance is seldom wasted', Tonie recalled. Read a little history. Have a good idea of where you want to go and why.

Why should we remember?

To honor and to acknowledge those living and dead who suffered and died on our behalf, Valmai supposed. How else are we to value liberty unless we know the price that has been paid for it?

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