Some of those who dropped into the same fields 65 years ago watched as members of today's 3 Para leapt from Dakota and Hercules aircraft.
In the early hours of 6 June 1944, Allied glider landings and parachute drops enabled British troops to take the strategically important Pegasus Bridge near Caen.
George "Les" Martin, 84, from Wigan, Lancs, was one of those who jumped. He said: "It was dark. You were huddled up in the plane and we got fed up.
"We jumped through a hole in the floor, not like the modern way. You were sat on the edge of the hole with nothing to hold you in. It could be quite terrifying."
As part of the commemorations, the Band of the Liberation marched across the bridge as onlookers watched from the first house in France liberated by the Allies on D-Day.
Owned then and now by the Gondree family, the property is today a cafe with a sign marking its place in history.
Veterans Frank Allen (left), 85, and Cyril Askew, 92, arrive in Normandy
The Normandy Veterans Association, for whom the occasion marks the last visit to France as a group, attended a service and parade at Monty's statue in Colleville-Montgomery at 1000 BST.
And at 1300 BST the Royal British Legion, schoolchildren and veterans laid a wreath at Bayeux International War Cemetery.
Later around 20 pipers will play as veteran Bill Millin visits the museum at Pegasus Bridge. On D-Day Mr Millin played his brigade ashore with his bagpipes.
In Asnelles around 80 children from London and the south east will plant flags in the beach with messages of thanks and talk to veterans about their experiences. Late on Friday evening there will be 25 simultaneous firework displays along the Normandy coastline followed by the illumination of Port Winston, a temporary harbour built by the British in Arromanches.
Pegasus Bridge was the first bridge captured by British troops on D-Day
The day will end with a midnight vigil attended by Chief of General Staff General Sir Richard Dannatt at Pegasus Bridge, Ranville.
The main commemorations will take place on Saturday.
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French officials have said they will award their highest military award - the Legion d'Honneur - to 10 British veterans on Friday.
The group includes several men who were among the first to land on the Normandy beaches on D-day and a female nurse who attended to the wounded on Gold beach.
Veterans' Minister Kevan Jones, who will be at the ceremony at Les Invalides in Paris, said: "I am immensely proud that these British veterans are today being decorated with such an honour, in recognition of their great courage and bravery."
On Tuesday, Clarence House confirmed that Prince Charles would travel to Normandy after he received a last-minute invitation from the French government.
The parachutists landed in the same fields as soldiers 65 years ago
French officials denied they had intended to snub the Royal Family after it emerged that the Queen had not been invited to the commemorations.
The Prince is expected to attend at least one event alongside US President Barack Obama, French President Nicolas Sarkozy and Gordon Brown.
They will gather at the Normandy American Cemetery, by Omaha Beach - code name for one of the five beaches where the Allied invasion of German-occupied France began.
Hundreds of British veterans will hold their main memorial event at the Arromanches beaches where thousands of UK and Canadian troops came ashore on 6 June 1944, and during the following days.
There will also be a Royal British Legion Service of Remembrance at Bayeux Cathedral.
Elsewhere, vandals have smashed eight Commonwealth war graves and 12 veterans' memorial stones at a cemetery in Wallsend on Tyneside. The Royal British Legion called the attack "heartless" and "disgusting".
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It was dark. You were huddled up in the plane
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