At this very moment 73 years ago today, Allied forces were consolidating five landing sites along a small stretch of the northern French coast.

It all began in the early hours of June 6, 1944, when British, Canadian and American paratroopers dropped (and glided) behind German front lines. They seized key bridges and fortifications, and disrupted German supply lines.

A couple of hours after dawn, the invasion force came ashore.

Following a day of bloody fighting, particularly at the Omaha beach approaches to Vierville-Sur-Mer and Saint-Pierre-du-Mont, Allied commanders could call D-Day a success. One hundred and fifty thousand Allied soldiers would be in France by the day's end.

It was a watershed moment not just in the history of the Second World War, but in world history.

Stepping onto the European continent, the land of ancient history and tradition, of William the Conqueror and the Bayeux Tapestry, young American servicemen laid the foundation for peace. Since the fall of Berlin in spring 1945 — that which D-Day made possible — no major war has been fought on European soil. That break with hundreds of years of European wars is not coincidental. It is the product of America's post-1945 guarantee of European democracy and peace.

And as I say, it all began at D-Day.

Two scenes from two different movies encapsulate D-Day's immense moral consequence.

First, the Schindler's List scene in which Schindler watches as the Krakow ghetto is liquidated. It captures Nazism's fanatical efficiency in motivating others towards great evil. Pursuing a warped racial purity, the Nazis were determined to purge "the sub-human." Had America not stood against them, they would have likely succeeded (remember, the Soviet Union relied heavily on allied supplies of vehicles and equipment).

Then's there's the scene from the D-Day epic, The Longest Day, in which the allied armada approaches the French coast. In this salute to vast American military power, the filmmakers want us to know what's at stake: freedom from tyranny and extermination.

Yes, it wasn't just Americans who made D-Day possible. Many British and many more Soviet soldiers fell before Nazism was defeated. Less well-known heroes, like British double-agent, Juan Pujol Garcia, were also instrumental. As was the home front. After all, without bombers, rifles, and tanks, success on D-Day would have been impossible. Factory workers, including many women, gave our soldiers the means of victory.

With persistence, by early August, the Allies had broken out of Normandy and were racing across France. They carried with them the world's better future.

D-Day will always be the ultimate metaphor for American exceptionalism.