Tony Abbott has joined Barack Obama and the Queen at the official 70th anniversary D-Day service in Normandy.
At the site where "the fate of humanity was played out and decided", seven Australians were among thousands of D-Day veterans honoured at 70th anniversary commemorations in France.
Prime Minister Tony Abbott, US President Barack Obama and the Queen joined a score of world leaders and World War II veterans in Normandy on Friday to remember the biggest seaborne assault in military history.
Mr Abbott described the anniversary as "one of those special days".
Mr Obama said he was "truly moved" to be in the presence of the veterans while French President Francois Hollande singled out the landings seven decades ago as the moment "the fate of humanity was played out and decided".
"The gratitude of France will never, ever end," Mr Holland said in his address at the official international ceremony at Sword Beach, Ouistreham.
"As the sun set on this longest day, a light came on across a Europe enslaved."
The landings in Normandy on June 6, 1944 caught the Germans by surprise and played a crucial role in the Allied victory in the war.
More than 3000 Australians fought in the campaign, mostly in the airforce, and some of them were present on Friday.
Former pilots Robert Cowper, Stuart Davis, Phillip Elger, Francis Evans, Ronald Houghton, Billy Purdy and Frederick Riley joined Mr Abbott for the visit to France.
All have been recognised with France's prestigious Legion of Honour.
Mr Cowper, while harbouring mixed emotions, said it was a honour to return to the site where he and so many of his mates fought on D-Day.
"It's wonderful as an old man of 91 - it's like coming home," Mr Cowper said.
"We shot down quite a lot of German bombers and all the ones we shot down were big bombers carrying radio controlled bombs.
".... Looking down, even though we were making a contribution, I remember feeling empathy for all the poor buggers fighting on the ground."
Many veterans were forced to endure a warm French afternoon as Friday's main service ran well behind schedule.
Hollande welcomed the world leaders one by one ahead of a ceremony in which the horror of 70 years ago was re-enacted by performers.
Earlier at an American service, Mr Obama hailed to bravery of those who breached "Hitler's Wall" and secured today's era of democracy and freedom.
Mr Abbott joined Prince Charles and UK Prime Minister David Cameron at a British service in the morning at the picturesque Bayeux Cathedral.
He also met briefly with the Queen at another ceremony at the Bayeux Cemetery, stopping beforehand at the graves of Flight Sergeant Malcolm Robert Burgess and Pilot Officer Roland Gilbert Ward - two of the 14 Australians killed in battle on D-Day.
"D-Day was a day that changed the world," Mr Abbott said.
The Prime Minister will on Saturday turn his attention to World War I when he visits the Western Front, including the Australian National Memorial at Villers-Bretonneux.
He will then depart for Canada and the US, where he will hold formal talks with Mr Obama.
The American President came face to face with Russian counterpart Vladimir Putin on Friday amid diplomatic wrangling over the Ukraine crisis, with the pair engaging in a brief, informal chat.