Emotional Biden, 81, surrounds himself with an older generation and invokes the heroes of the D-Day to warn of the 'tyranny' that could come with Trump

The last notes of Taps had faded away and smoke from a military gun salute was billowing through the Normandy cemetery as the roar of the four F-35s rose to a thunder.

As one of the pilots opened their throttle and accelerated into the heavens in the 'missing man' formation, President Joe Biden got emotional.

He had spent the day joshing with the last surviving veterans of the D-Day landing before delivering a speech that tied their heroics with modern war and dictators, and it all came flooding out in the form of a fist pump.

'To surrender to bullies, to bow down to dictators, is simply unthinkable,' he said moments earlier, with 30 D-Day veterans sitting behind him.

'If we were to do that, it means we'd be forgetting what happened here on these hallowed beaches.'

In front of him, lay the sand of Omaha Beach, where about 2,400 American servicemen died on June 6, 1944.

An emotional President Joe Biden pumps his fist at the end of his remarks on the 80th anniversary of D-Day during the 'missing man' flyover in Normandy 

They were part of the largest amphibian landing in history, and the start of the march on Berlin.

It was the sort of day when Biden is in his element: Mourning the dead, celebrating the eventual victory, and tying the thread of history to his big message that democracy is fragile and must be defended.

And his appearance will no doubt live on until November in the form of campaign adverts.

Biden flew into Normandy on Thursday morning, along with other world leaders assembling for the anniversary.

In a glass-sided gazebo, with views down to the beach and water, he met 30 of the men who risked their lives in the assault.

It is a rare occasion when the 81-year-old president is surrounded by an older generation, but he reveled in their company, handing out specially commissioned challenge coins and joshing with them.

'The greatest generation ever, man,' he said to one veteran, who told the president he was 102.

Those that could stand, stood to shake hands with the president. Some needed the first lady's steady grip to help them stay upright.

Overhead, the sun beat down. The English Channel was docile, the sky clear - much better conditions than on D-Day when the Allies knew they only had a window of hours to launch their invasion and deliver 150,000 troops into Nazi-occupied France.

At one point Biden bent his knees to look directly into the eyes of a veteran, gripping his wrists as he did so. 'You saved the world,' was his message.

It was the sort of day when Biden is in his element: Mourning the dead, celebrating the eventual victory, and tying the thread of history to his big message that democracy is fragile and must be defended

Biden greets Second World War veteran Victor Chaney after he was given the Chevalier de la Legion d'Honneur (French Legion of Honour) during the ceremony marking the 80th anniversary of D-Day

Another dropped himself heavily into his wheelchair after meeting the president.

'Don't get old,' said Army veteran Robert Gibson, 100, from New Jersey. Biden was a toddler when Gibson and his comrades arrived on Utah Beach in the second wave of troops.

Their frailty is a reminder that there will not be many more chances to see the veterans in Normandy, and Biden made the most of it, encouraging everyone to join in a round of 'Happy Birthday' when he found out that one was to celebrate his birthday on Saturday.

Not far away, two titans of World War Two movie making, Tom Hanks and Steven Spielberg, chatted with other in the shade of a tree. 

Until, that is Sen. Ted Cruz turned up.

'Tom Hanks managed to keep away but Spielberg got stuck talking to him and looked like he hated every second of it,' said a bystander.

As well as using his big speech to remember the sacrifice of so many, Biden was just one of the world leaders who used the echo of history to deliver a very contemporary message. 

In his case, it included a hint that U.S. commitments around the globe are on the line in November's election, when he faces off against Donald Trump and his more isolationist manifesto.

Trump has said he would not defend allies that are 'delinquent' in their defense spending.

'Democracy is never guaranteed,' said Biden in his speech. 'Every generation must preserve it, defend it and fight for it. That's the test of the ages'

'Don't get old,' said Army veteran Robert Gibson, 100, from New Jersey. Biden was a toddler when Gibson and his comrades arrived on Utah Beach in the second wave of troops

It is a rare occasion when the 81-year-old president is surrounded by an older generation

Biden flew into Normandy on Thursday morning, along with other world leaders assembling for the anniversary

'We must remember that the fact that they were heroes here that day does not absolve us of what we have to do today. Democracy is never guaranteed,' said Biden.

'Every generation must preserve it, defend it and fight for it. That's the test of the ages.'

That means standing with Ukraine, whose president, Volodymyr Zelenky, was in Normandy for the commemorations.

'Isolationism was not the answer 80 years ago and is not the answer today,' Biden said in his speech, triggering his biggest round of applause.

Biden reveled in their company, handing out specially commissioned challenge coins and joshing with them

'We will not walk away,' Biden said. 'Because if we do, Ukraine will be subjugated and it will not end there.'

In all, 180 veterans of the Normandy campaign were on hand to hear him speak. They arrived with granddaughters and grandsons, wearing caps that identified their units, with medals pinned to their chests.

As they left they stopped for selfies with young service members, who were clearly in awe of the men who went before them. 

Some ran around with the glee of fans at a Taylor Swift concert.