Pipe Major Trevor Macey-Lillie, of 19th Regiment Royal Artillery (The Scottish Gunners), performed Highland Laddie at the port in Arromanches at 6.26am to signal the moment the first British soldier landed on Gold beach.
Events on Thursday include a parade in the town square attended by Veterans Minister Tobias Ellwood and chief of Ministry of Defence general staff Mark Carleton-Smith as well as a Red Arrows flypast and a firework display.
This morning Theresa May attended an inauguration ceremony in Normandy for a memorial to commemorate more than 20,000 members of the British armed forces who died there in summer 1944.
The British Normandy Memorial, funded by the Normandy Memorial Trust, is being built on a hillside in Ver-sur-Mer, overlooking Gold Beach, and will record the names of 22,442 members of the British armed forces who died in the D-Day landings and Battle of Normandy.
As one of her last official engagements as Prime Minister, Mrs May was joined by French President Emmanuel Macron for the unveiling of a sculpture by David Williams-Ellis to mark the beginning of construction for the memorial.
Mrs May paid tribute to the bravery and sacrifice of the "greatest generation" of service personnel who served during the landings.
"If one day can be said to have determined the fate of generations to come, in France, in Britain, in Europe and in the world, that day was the 6 June 1944," she said.
"More than 156,000 men landed on D-Day, of which 83,000 were from Britain and the Commonwealth.
She added: "Over a quarter of a million more supported operations from air and sea, while the French Resistance carried out extraordinary acts of bravery from behind enemy lines.
"Many were terribly wounded, and many made the ultimate sacrifice that day, and in the fierce sacrifice that followed, as together our Allied nations sought to release Europe from the grip of fascism."
The Prime Minister read the names of several British troops who were killed during the D-Day landings and the Battle of Normandy.
"These young men belonged to a very special generation, the greatest generation," she said.
"A generation whose incomparable spirit shaped our postwar world.
"They didn't boast. They didn't fuss. They served."