Up to a million people are expected in Normandy for this weekend's 60th D-Day anniversary celebrations.
French authorities have mounted what one interior ministry official yesterday called the country's biggest ever peace-time security operation as seventeen heads of state and government, including Mr George Bush, Mr Vladimir Putin, Mr Tony Blair, Mr Gerhard Schröder, Mr Jacques Chirac and Queen Elizabeth II are to arrive in the region from today.
A restricted zone 20 miles deep has been drawn along 60 miles of coastline as a massive security operation is in place with some 19,000 French military personnel and police out in force.
Thousands of veterans have made their way to the northern coast of France to return to the former battle zones where they began the Second Front.
Of three million men who fought in the subsequent battle around 250,000 were killed.
On 6 June 1944, 156,000 troops landed on the Normandy beaches from some 5,000 allied vessels.
Allied forces suffered 10,000 casualties, 3,000 of whom were dead - mostly airborne troops or those who had landed at Omaha Beach.
A flotilla will set sail from Portsmouth and Southampton in a "symbolic crossing" including a French, US, and Canadian warship to represent the forces that took part in the invasion.
Consisting of warships, ferries, a cruise ship and other vessels, it will carry hundreds of D-Day veterans to the commemorations in France.
One Irish veteran, Mr Allen from Lisburn, recalled escorting troop ships to the beaches, protecting them from submarine and E-boat attack. He said: "It's mild today, but it was a bit rough back then, they had had to postpone the invasion for 24 hours.
"It will bring back a lot of memories. We are sailing very close to where we were when we were going to war, the same beaches."
And for Mr Allen the flotilla will be particularly poignant. At its head will be HMS Gloucester, a modern frigate. But its predecessor was sunk in Crete during World War II - and one of Mr Allen 's friends went down with it.
"The old Gloucester was sunk, a mate died. He was killed. He was only 18." The veteran was with his nephew, George Clarke, also from Northern Ireland. Mr Clarke said: "I have been to France before for a holiday but this is different, meeting people who were there for the invasion.