After World War II there was a desire in Europe to end the continent's violent history. Trade and co-operation would be promoted, but few could have predicted how it would shape the continent.
Two summers ago I attended the celebrations to mark the 60th anniversary of D-Day.
On D-Day alone up to 3,000 Allied troops died
I watched the old men gather for the last time on the beaches that they had stormed so long ago.
I followed them to the graves of friends who had not made it.
It was striking that the living rankled at any reference to the courage of their youth or the sacrifice they had made.
They were not there to receive tribute but to pay it, to those they left behind in the soil of liberated France.
What is now the European Union came out of their experience.
After 1945 a consensus formed on the European continent that there now existed an opportunity to remake the European order in such a way as to turn the page on Europe's bloody past.
To make war between France and Germany - Europe's historic curse - not just difficult or undesirable, but actually impossible.
I have spent much of this year tracking down the men and women who were in the vanguard of building what they believed was a better world.
The Dutchman Max Kohnstamm is 92 now and I found him in Amsterdam in a house not far from where he had been arrested, in 1942, by Dutch police collaborating with the Nazi occupiers.
He was then interned in a concentration camp and spent the rest of the war watching fellow prisoners being led away for execution, and waiting for his turn, which, miraculously, never came.
"When it was all over I saw some Dutch women being seized by angry crowds," he told me, "They were accused of having had relations with German men and now they were having their heads shaved as an act of vengeance.
The post-war French and German governments changed the nature of the nation state in Europe
"And I thought, no, not again. We must not have another period of revenge."
Konstamm joined the Secretariat of the European Coal and Steel Community in Luxembourg in 1951.
Monnet believed pooling countries' industries could bring peace
Its Secretary General was the Frenchman Jean Monnet, widely recognised now throughout Europe as the founding father of the European Union.
The post-war French and German governments changed the nature of the nation state in Europe by agreeing a historic compromise: surrender some national sovereignty in return for peace and prosperity.
It has been the compromise that every new member has been asked, and agreed, to make for the last 50 years.
Max Kohnstamm put me in touch with a man he described as "my dearest German friend, even now" who he met in those early days in Luxembourg.
Winrich Bier also worked for Jean Monnet. He had been a Wehrmacht officer, a professional soldier of the Third Reich.
He had been sent by Hitler in person to plan the victory parade in occupied Paris.
He served in Von Paulus' staff on the Stalingrad front and had been chosen by his senior officers to fly out of a besieged pocket, return to Berlin and tell Hitler in person that the military situation was hopeless.
Now he was forming a life-long friendship with a man who had been held in a concentration camp as an enemy of the Reich.
When I went to see him at his home in Dusseldorf, Bier did not want to talk about the war.
He wanted to talk about the peace.
About the men and women who gathered around Jean Monnet to put the past behind them and learn the lessons of history.
"I told Monnet straight that I had been a German officer," he said, "I didn't want anyone to think I was hiding it."
Monnet said: "Well we're building a new Europe now and Germany must be part of it."
The six original members - France and Germany, Italy, Belgium, Luxembourg and Holland - wanted Britain to be a founder member.
They invited the then Foreign Secretary Harold MacMillan to attend a summit at Messina in Italy, MacMillan scribbled a note on the memorandum: "Tell them I'm occupied with Cyprus" it read.
Earlier the Labour Prime Minister Clement Atlee had dismissed the project as "six nations, four of whom we had to rescue from the other two."
Harold Macmillan was reluctant to be involved in European talks
I think that stark difference in vision casts its shadow to this day.
Sixty years on, that war-time and post-war experience remains the source of Britain's pained ambivalence about its European identity - its very commitment to Europe.
The British have never drawn the same visceral, highly charged connection between European union and the prevention of war that their continental neighbours drew.
For the British, whose country never fell, the European project has never been about building a better world. It has been about something much more technical, less emotional.
It has been about trade, about markets, about economic growth.
Britain remains the reluctant European, half-in, half-not.
That ambivalence has its origins in the 1940s, in the days when those old men I met on the beaches of Normandy two years ago were young.
From Our Own Correspondent was broadcast on Saturday, 8 July, 2006 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.